G2 Science K223, K224 and K225 can show a stable measurement even while processes continue. A constant water level can coexist with equal inflow and outflow; constant speed can coexist with motion; a stable population can coexist with births and deaths. Stability does not always mean inactivity.
This one-hundred-and-twenty-seventh Learner’s Guide develops dynamic-balance reasoning. It extends Vol 0111 Rate Versus Amount and Vol 0115 Baseline Drift.
The dynamic-balance question
When an observed quantity is stable, ask whether the underlying processes have stopped or whether opposing inputs and outputs are balancing. Name the rates on both sides before concluding that nothing is happening.
1. constant water level with inflow/outflow
For constant water level with inflow/outflow, identify the measured state variable and the processes that can increase or decrease it. A stable state occurs when the net change is approximately zero over the relevant interval.
For practice, draw two arrows into and out of a state. Make both arrows larger while keeping them equal. The state can remain stable even though turnover increases. Then make one arrow larger and predict the direction of change.
Do not label every flat graph as equilibrium. A plateau can arise from saturation, depletion, measurement ceiling or a chosen time window. Use mechanism and design evidence to decide whether dynamic balance is the best explanation.
2. constant population with births/deaths
For constant population with births/deaths, identify the measured state variable and the processes that can increase or decrease it. A stable state occurs when the net change is approximately zero over the relevant interval.
For practice, draw two arrows into and out of a state. Make both arrows larger while keeping them equal. The state can remain stable even though turnover increases. Then make one arrow larger and predict the direction of change.
Do not label every flat graph as equilibrium. A plateau can arise from saturation, depletion, measurement ceiling or a chosen time window. Use mechanism and design evidence to decide whether dynamic balance is the best explanation.
3. constant stock with production/removal
For constant stock with production/removal, identify the measured state variable and the processes that can increase or decrease it. A stable state occurs when the net change is approximately zero over the relevant interval.
For practice, draw two arrows into and out of a state. Make both arrows larger while keeping them equal. The state can remain stable even though turnover increases. Then make one arrow larger and predict the direction of change.
Do not label every flat graph as equilibrium. A plateau can arise from saturation, depletion, measurement ceiling or a chosen time window. Use mechanism and design evidence to decide whether dynamic balance is the best explanation.
4. constant temperature with equal energy transfers
For constant temperature with equal energy transfers, identify the measured state variable and the processes that can increase or decrease it. A stable state occurs when the net change is approximately zero over the relevant interval.
For practice, draw two arrows into and out of a state. Make both arrows larger while keeping them equal. The state can remain stable even though turnover increases. Then make one arrow larger and predict the direction of change.
Do not label every flat graph as equilibrium. A plateau can arise from saturation, depletion, measurement ceiling or a chosen time window. Use mechanism and design evidence to decide whether dynamic balance is the best explanation.
5. constant concentration with balanced addition/removal
For constant concentration with balanced addition/removal, identify the measured state variable and the processes that can increase or decrease it. A stable state occurs when the net change is approximately zero over the relevant interval.
For practice, draw two arrows into and out of a state. Make both arrows larger while keeping them equal. The state can remain stable even though turnover increases. Then make one arrow larger and predict the direction of change.
Do not label every flat graph as equilibrium. A plateau can arise from saturation, depletion, measurement ceiling or a chosen time window. Use mechanism and design evidence to decide whether dynamic balance is the best explanation.
6. constant gas amount with equal input/output
For constant gas amount with equal input/output, identify the measured state variable and the processes that can increase or decrease it. A stable state occurs when the net change is approximately zero over the relevant interval.
For practice, draw two arrows into and out of a state. Make both arrows larger while keeping them equal. The state can remain stable even though turnover increases. Then make one arrow larger and predict the direction of change.
Do not label every flat graph as equilibrium. A plateau can arise from saturation, depletion, measurement ceiling or a chosen time window. Use mechanism and design evidence to decide whether dynamic balance is the best explanation.
7. constant charge state with balanced flows in context
For constant charge state with balanced flows in context, identify the measured state variable and the processes that can increase or decrease it. A stable state occurs when the net change is approximately zero over the relevant interval.
For practice, draw two arrows into and out of a state. Make both arrows larger while keeping them equal. The state can remain stable even though turnover increases. Then make one arrow larger and predict the direction of change.
Do not label every flat graph as equilibrium. A plateau can arise from saturation, depletion, measurement ceiling or a chosen time window. Use mechanism and design evidence to decide whether dynamic balance is the best explanation.
8. constant body condition under regulation
For constant body condition under regulation, identify the measured state variable and the processes that can increase or decrease it. A stable state occurs when the net change is approximately zero over the relevant interval.
For practice, draw two arrows into and out of a state. Make both arrows larger while keeping them equal. The state can remain stable even though turnover increases. Then make one arrow larger and predict the direction of change.
Do not label every flat graph as equilibrium. A plateau can arise from saturation, depletion, measurement ceiling or a chosen time window. Use mechanism and design evidence to decide whether dynamic balance is the best explanation.
9. constant blood-like variable in simplified homeostasis context
For constant blood-like variable in simplified homeostasis context, identify the measured state variable and the processes that can increase or decrease it. A stable state occurs when the net change is approximately zero over the relevant interval.
For practice, draw two arrows into and out of a state. Make both arrows larger while keeping them equal. The state can remain stable even though turnover increases. Then make one arrow larger and predict the direction of change.
Do not label every flat graph as equilibrium. A plateau can arise from saturation, depletion, measurement ceiling or a chosen time window. Use mechanism and design evidence to decide whether dynamic balance is the best explanation.
10. stable room temperature
For stable room temperature, identify the measured state variable and the processes that can increase or decrease it. A stable state occurs when the net change is approximately zero over the relevant interval.
For practice, draw two arrows into and out of a state. Make both arrows larger while keeping them equal. The state can remain stable even though turnover increases. Then make one arrow larger and predict the direction of change.
Do not label every flat graph as equilibrium. A plateau can arise from saturation, depletion, measurement ceiling or a chosen time window. Use mechanism and design evidence to decide whether dynamic balance is the best explanation.
11. stable mass in open flow system
For stable mass in open flow system, identify the measured state variable and the processes that can increase or decrease it. A stable state occurs when the net change is approximately zero over the relevant interval.
For practice, draw two arrows into and out of a state. Make both arrows larger while keeping them equal. The state can remain stable even though turnover increases. Then make one arrow larger and predict the direction of change.
Do not label every flat graph as equilibrium. A plateau can arise from saturation, depletion, measurement ceiling or a chosen time window. Use mechanism and design evidence to decide whether dynamic balance is the best explanation.
12. stable volume with continuous flow
For stable volume with continuous flow, identify the measured state variable and the processes that can increase or decrease it. A stable state occurs when the net change is approximately zero over the relevant interval.
For practice, draw two arrows into and out of a state. Make both arrows larger while keeping them equal. The state can remain stable even though turnover increases. Then make one arrow larger and predict the direction of change.
Do not label every flat graph as equilibrium. A plateau can arise from saturation, depletion, measurement ceiling or a chosen time window. Use mechanism and design evidence to decide whether dynamic balance is the best explanation.
13. stable ecosystem population over interval
For stable ecosystem population over interval, identify the measured state variable and the processes that can increase or decrease it. A stable state occurs when the net change is approximately zero over the relevant interval.
For practice, draw two arrows into and out of a state. Make both arrows larger while keeping them equal. The state can remain stable even though turnover increases. Then make one arrow larger and predict the direction of change.
Do not label every flat graph as equilibrium. A plateau can arise from saturation, depletion, measurement ceiling or a chosen time window. Use mechanism and design evidence to decide whether dynamic balance is the best explanation.
14. stable predator/prey average with turnover
For stable predator/prey average with turnover, identify the measured state variable and the processes that can increase or decrease it. A stable state occurs when the net change is approximately zero over the relevant interval.
For practice, draw two arrows into and out of a state. Make both arrows larger while keeping them equal. The state can remain stable even though turnover increases. Then make one arrow larger and predict the direction of change.
Do not label every flat graph as equilibrium. A plateau can arise from saturation, depletion, measurement ceiling or a chosen time window. Use mechanism and design evidence to decide whether dynamic balance is the best explanation.
15. stable nutrient level with uptake/replacement
For stable nutrient level with uptake/replacement, identify the measured state variable and the processes that can increase or decrease it. A stable state occurs when the net change is approximately zero over the relevant interval.
For practice, draw two arrows into and out of a state. Make both arrows larger while keeping them equal. The state can remain stable even though turnover increases. Then make one arrow larger and predict the direction of change.
Do not label every flat graph as equilibrium. A plateau can arise from saturation, depletion, measurement ceiling or a chosen time window. Use mechanism and design evidence to decide whether dynamic balance is the best explanation.
16. steady reaction output with continuous supply context
For steady reaction output with continuous supply context, identify the measured state variable and the processes that can increase or decrease it. A stable state occurs when the net change is approximately zero over the relevant interval.
For practice, draw two arrows into and out of a state. Make both arrows larger while keeping them equal. The state can remain stable even though turnover increases. Then make one arrow larger and predict the direction of change.
Do not label every flat graph as equilibrium. A plateau can arise from saturation, depletion, measurement ceiling or a chosen time window. Use mechanism and design evidence to decide whether dynamic balance is the best explanation.
17. steady sensor reading after warm-up
For steady sensor reading after warm-up, identify the measured state variable and the processes that can increase or decrease it. A stable state occurs when the net change is approximately zero over the relevant interval.
For practice, draw two arrows into and out of a state. Make both arrows larger while keeping them equal. The state can remain stable even though turnover increases. Then make one arrow larger and predict the direction of change.
Do not label every flat graph as equilibrium. A plateau can arise from saturation, depletion, measurement ceiling or a chosen time window. Use mechanism and design evidence to decide whether dynamic balance is the best explanation.
18. steady current in stable circuit context
For steady current in stable circuit context, identify the measured state variable and the processes that can increase or decrease it. A stable state occurs when the net change is approximately zero over the relevant interval.
For practice, draw two arrows into and out of a state. Make both arrows larger while keeping them equal. The state can remain stable even though turnover increases. Then make one arrow larger and predict the direction of change.
Do not label every flat graph as equilibrium. A plateau can arise from saturation, depletion, measurement ceiling or a chosen time window. Use mechanism and design evidence to decide whether dynamic balance is the best explanation.
19. steady speed with balanced forces
For steady speed with balanced forces, identify the measured state variable and the processes that can increase or decrease it. A stable state occurs when the net change is approximately zero over the relevant interval.
For practice, draw two arrows into and out of a state. Make both arrows larger while keeping them equal. The state can remain stable even though turnover increases. Then make one arrow larger and predict the direction of change.
Do not label every flat graph as equilibrium. A plateau can arise from saturation, depletion, measurement ceiling or a chosen time window. Use mechanism and design evidence to decide whether dynamic balance is the best explanation.
20. zero acceleration with nonzero speed
For zero acceleration with nonzero speed, identify the measured state variable and the processes that can increase or decrease it. A stable state occurs when the net change is approximately zero over the relevant interval.
For practice, draw two arrows into and out of a state. Make both arrows larger while keeping them equal. The state can remain stable even though turnover increases. Then make one arrow larger and predict the direction of change.
Do not label every flat graph as equilibrium. A plateau can arise from saturation, depletion, measurement ceiling or a chosen time window. Use mechanism and design evidence to decide whether dynamic balance is the best explanation.
21. zero net force with multiple forces
For zero net force with multiple forces, identify the measured state variable and the processes that can increase or decrease it. A stable state occurs when the net change is approximately zero over the relevant interval.
For practice, draw two arrows into and out of a state. Make both arrows larger while keeping them equal. The state can remain stable even though turnover increases. Then make one arrow larger and predict the direction of change.
Do not label every flat graph as equilibrium. A plateau can arise from saturation, depletion, measurement ceiling or a chosen time window. Use mechanism and design evidence to decide whether dynamic balance is the best explanation.
22. zero net change with active processes
For zero net change with active processes, identify the measured state variable and the processes that can increase or decrease it. A stable state occurs when the net change is approximately zero over the relevant interval.
For practice, draw two arrows into and out of a state. Make both arrows larger while keeping them equal. The state can remain stable even though turnover increases. Then make one arrow larger and predict the direction of change.
Do not label every flat graph as equilibrium. A plateau can arise from saturation, depletion, measurement ceiling or a chosen time window. Use mechanism and design evidence to decide whether dynamic balance is the best explanation.
23. no net water movement while molecules move
For no net water movement while molecules move, identify the measured state variable and the processes that can increase or decrease it. A stable state occurs when the net change is approximately zero over the relevant interval.
For practice, draw two arrows into and out of a state. Make both arrows larger while keeping them equal. The state can remain stable even though turnover increases. Then make one arrow larger and predict the direction of change.
Do not label every flat graph as equilibrium. A plateau can arise from saturation, depletion, measurement ceiling or a chosen time window. Use mechanism and design evidence to decide whether dynamic balance is the best explanation.
24. diffusion at no net concentration change in simplified context
For diffusion at no net concentration change in simplified context, identify the measured state variable and the processes that can increase or decrease it. A stable state occurs when the net change is approximately zero over the relevant interval.
For practice, draw two arrows into and out of a state. Make both arrows larger while keeping them equal. The state can remain stable even though turnover increases. Then make one arrow larger and predict the direction of change.
Do not label every flat graph as equilibrium. A plateau can arise from saturation, depletion, measurement ceiling or a chosen time window. Use mechanism and design evidence to decide whether dynamic balance is the best explanation.
25. dynamic particle motion in stable temperature
For dynamic particle motion in stable temperature, identify the measured state variable and the processes that can increase or decrease it. A stable state occurs when the net change is approximately zero over the relevant interval.
For practice, draw two arrows into and out of a state. Make both arrows larger while keeping them equal. The state can remain stable even though turnover increases. Then make one arrow larger and predict the direction of change.
Do not label every flat graph as equilibrium. A plateau can arise from saturation, depletion, measurement ceiling or a chosen time window. Use mechanism and design evidence to decide whether dynamic balance is the best explanation.
26. evaporation and condensation balance in closed context
For evaporation and condensation balance in closed context, identify the measured state variable and the processes that can increase or decrease it. A stable state occurs when the net change is approximately zero over the relevant interval.
For practice, draw two arrows into and out of a state. Make both arrows larger while keeping them equal. The state can remain stable even though turnover increases. Then make one arrow larger and predict the direction of change.
Do not label every flat graph as equilibrium. A plateau can arise from saturation, depletion, measurement ceiling or a chosen time window. Use mechanism and design evidence to decide whether dynamic balance is the best explanation.
27. melting/freezing balance concept where conditions support
For melting/freezing balance concept where conditions support, identify the measured state variable and the processes that can increase or decrease it. A stable state occurs when the net change is approximately zero over the relevant interval.
For practice, draw two arrows into and out of a state. Make both arrows larger while keeping them equal. The state can remain stable even though turnover increases. Then make one arrow larger and predict the direction of change.
Do not label every flat graph as equilibrium. A plateau can arise from saturation, depletion, measurement ceiling or a chosen time window. Use mechanism and design evidence to decide whether dynamic balance is the best explanation.
28. photosynthesis and respiration net balance in organism/plant context
For photosynthesis and respiration net balance in organism/plant context, identify the measured state variable and the processes that can increase or decrease it. A stable state occurs when the net change is approximately zero over the relevant interval.
For practice, draw two arrows into and out of a state. Make both arrows larger while keeping them equal. The state can remain stable even though turnover increases. Then make one arrow larger and predict the direction of change.
Do not label every flat graph as equilibrium. A plateau can arise from saturation, depletion, measurement ceiling or a chosen time window. Use mechanism and design evidence to decide whether dynamic balance is the best explanation.
29. oxygen production and consumption balance
For oxygen production and consumption balance, identify the measured state variable and the processes that can increase or decrease it. A stable state occurs when the net change is approximately zero over the relevant interval.
For practice, draw two arrows into and out of a state. Make both arrows larger while keeping them equal. The state can remain stable even though turnover increases. Then make one arrow larger and predict the direction of change.
Do not label every flat graph as equilibrium. A plateau can arise from saturation, depletion, measurement ceiling or a chosen time window. Use mechanism and design evidence to decide whether dynamic balance is the best explanation.
30. resource input and use balance
For resource input and use balance, identify the measured state variable and the processes that can increase or decrease it. A stable state occurs when the net change is approximately zero over the relevant interval.
For practice, draw two arrows into and out of a state. Make both arrows larger while keeping them equal. The state can remain stable even though turnover increases. Then make one arrow larger and predict the direction of change.
Do not label every flat graph as equilibrium. A plateau can arise from saturation, depletion, measurement ceiling or a chosen time window. Use mechanism and design evidence to decide whether dynamic balance is the best explanation.
31. homeostatic feedback
For homeostatic feedback, identify the measured state variable and the processes that can increase or decrease it. A stable state occurs when the net change is approximately zero over the relevant interval.
For practice, draw two arrows into and out of a state. Make both arrows larger while keeping them equal. The state can remain stable even though turnover increases. Then make one arrow larger and predict the direction of change.
Do not label every flat graph as equilibrium. A plateau can arise from saturation, depletion, measurement ceiling or a chosen time window. Use mechanism and design evidence to decide whether dynamic balance is the best explanation.
32. negative feedback
For negative feedback, identify the measured state variable and the processes that can increase or decrease it. A stable state occurs when the net change is approximately zero over the relevant interval.
For practice, draw two arrows into and out of a state. Make both arrows larger while keeping them equal. The state can remain stable even though turnover increases. Then make one arrow larger and predict the direction of change.
Do not label every flat graph as equilibrium. A plateau can arise from saturation, depletion, measurement ceiling or a chosen time window. Use mechanism and design evidence to decide whether dynamic balance is the best explanation.
33. set point
For set point, identify the measured state variable and the processes that can increase or decrease it. A stable state occurs when the net change is approximately zero over the relevant interval.
For practice, draw two arrows into and out of a state. Make both arrows larger while keeping them equal. The state can remain stable even though turnover increases. Then make one arrow larger and predict the direction of change.
Do not label every flat graph as equilibrium. A plateau can arise from saturation, depletion, measurement ceiling or a chosen time window. Use mechanism and design evidence to decide whether dynamic balance is the best explanation.
34. operating range
For operating range, identify the measured state variable and the processes that can increase or decrease it. A stable state occurs when the net change is approximately zero over the relevant interval.
For practice, draw two arrows into and out of a state. Make both arrows larger while keeping them equal. The state can remain stable even though turnover increases. Then make one arrow larger and predict the direction of change.
Do not label every flat graph as equilibrium. A plateau can arise from saturation, depletion, measurement ceiling or a chosen time window. Use mechanism and design evidence to decide whether dynamic balance is the best explanation.
35. steady state versus equilibrium
For steady state versus equilibrium, identify the measured state variable and the processes that can increase or decrease it. A stable state occurs when the net change is approximately zero over the relevant interval.
For practice, draw two arrows into and out of a state. Make both arrows larger while keeping them equal. The state can remain stable even though turnover increases. Then make one arrow larger and predict the direction of change.
Do not label every flat graph as equilibrium. A plateau can arise from saturation, depletion, measurement ceiling or a chosen time window. Use mechanism and design evidence to decide whether dynamic balance is the best explanation.
36. equilibrium versus no activity
For equilibrium versus no activity, identify the measured state variable and the processes that can increase or decrease it. A stable state occurs when the net change is approximately zero over the relevant interval.
For practice, draw two arrows into and out of a state. Make both arrows larger while keeping them equal. The state can remain stable even though turnover increases. Then make one arrow larger and predict the direction of change.
Do not label every flat graph as equilibrium. A plateau can arise from saturation, depletion, measurement ceiling or a chosen time window. Use mechanism and design evidence to decide whether dynamic balance is the best explanation.
37. constant graph versus zero mechanism
For constant graph versus zero mechanism, identify the measured state variable and the processes that can increase or decrease it. A stable state occurs when the net change is approximately zero over the relevant interval.
For practice, draw two arrows into and out of a state. Make both arrows larger while keeping them equal. The state can remain stable even though turnover increases. Then make one arrow larger and predict the direction of change.
Do not label every flat graph as equilibrium. A plateau can arise from saturation, depletion, measurement ceiling or a chosen time window. Use mechanism and design evidence to decide whether dynamic balance is the best explanation.
38. flat line with opposing rates
For flat line with opposing rates, identify the measured state variable and the processes that can increase or decrease it. A stable state occurs when the net change is approximately zero over the relevant interval.
For practice, draw two arrows into and out of a state. Make both arrows larger while keeping them equal. The state can remain stable even though turnover increases. Then make one arrow larger and predict the direction of change.
Do not label every flat graph as equilibrium. A plateau can arise from saturation, depletion, measurement ceiling or a chosen time window. Use mechanism and design evidence to decide whether dynamic balance is the best explanation.
39. plateau after saturation
For plateau after saturation, identify the measured state variable and the processes that can increase or decrease it. A stable state occurs when the net change is approximately zero over the relevant interval.
For practice, draw two arrows into and out of a state. Make both arrows larger while keeping them equal. The state can remain stable even though turnover increases. Then make one arrow larger and predict the direction of change.
Do not label every flat graph as equilibrium. A plateau can arise from saturation, depletion, measurement ceiling or a chosen time window. Use mechanism and design evidence to decide whether dynamic balance is the best explanation.
40. plateau from balance
For plateau from balance, identify the measured state variable and the processes that can increase or decrease it. A stable state occurs when the net change is approximately zero over the relevant interval.
For practice, draw two arrows into and out of a state. Make both arrows larger while keeping them equal. The state can remain stable even though turnover increases. Then make one arrow larger and predict the direction of change.
Do not label every flat graph as equilibrium. A plateau can arise from saturation, depletion, measurement ceiling or a chosen time window. Use mechanism and design evidence to decide whether dynamic balance is the best explanation.
41. plateau from depletion
For plateau from depletion, identify the measured state variable and the processes that can increase or decrease it. A stable state occurs when the net change is approximately zero over the relevant interval.
For practice, draw two arrows into and out of a state. Make both arrows larger while keeping them equal. The state can remain stable even though turnover increases. Then make one arrow larger and predict the direction of change.
Do not label every flat graph as equilibrium. A plateau can arise from saturation, depletion, measurement ceiling or a chosen time window. Use mechanism and design evidence to decide whether dynamic balance is the best explanation.
42. plateau from instrument ceiling
For plateau from instrument ceiling, identify the measured state variable and the processes that can increase or decrease it. A stable state occurs when the net change is approximately zero over the relevant interval.
For practice, draw two arrows into and out of a state. Make both arrows larger while keeping them equal. The state can remain stable even though turnover increases. Then make one arrow larger and predict the direction of change.
Do not label every flat graph as equilibrium. A plateau can arise from saturation, depletion, measurement ceiling or a chosen time window. Use mechanism and design evidence to decide whether dynamic balance is the best explanation.
43. same endpoint different internal flux
For same endpoint different internal flux, identify the measured state variable and the processes that can increase or decrease it. A stable state occurs when the net change is approximately zero over the relevant interval.
For practice, draw two arrows into and out of a state. Make both arrows larger while keeping them equal. The state can remain stable even though turnover increases. Then make one arrow larger and predict the direction of change.
Do not label every flat graph as equilibrium. A plateau can arise from saturation, depletion, measurement ceiling or a chosen time window. Use mechanism and design evidence to decide whether dynamic balance is the best explanation.
44. same total with continuous turnover
For same total with continuous turnover, identify the measured state variable and the processes that can increase or decrease it. A stable state occurs when the net change is approximately zero over the relevant interval.
For practice, draw two arrows into and out of a state. Make both arrows larger while keeping them equal. The state can remain stable even though turnover increases. Then make one arrow larger and predict the direction of change.
Do not label every flat graph as equilibrium. A plateau can arise from saturation, depletion, measurement ceiling or a chosen time window. Use mechanism and design evidence to decide whether dynamic balance is the best explanation.
45. input rate equals output rate
For input rate equals output rate, identify the measured state variable and the processes that can increase or decrease it. A stable state occurs when the net change is approximately zero over the relevant interval.
For practice, draw two arrows into and out of a state. Make both arrows larger while keeping them equal. The state can remain stable even though turnover increases. Then make one arrow larger and predict the direction of change.
Do not label every flat graph as equilibrium. A plateau can arise from saturation, depletion, measurement ceiling or a chosen time window. Use mechanism and design evidence to decide whether dynamic balance is the best explanation.
46. production rate equals removal rate
For production rate equals removal rate, identify the measured state variable and the processes that can increase or decrease it. A stable state occurs when the net change is approximately zero over the relevant interval.
For practice, draw two arrows into and out of a state. Make both arrows larger while keeping them equal. The state can remain stable even though turnover increases. Then make one arrow larger and predict the direction of change.
Do not label every flat graph as equilibrium. A plateau can arise from saturation, depletion, measurement ceiling or a chosen time window. Use mechanism and design evidence to decide whether dynamic balance is the best explanation.
47. heating rate equals cooling rate
For heating rate equals cooling rate, identify the measured state variable and the processes that can increase or decrease it. A stable state occurs when the net change is approximately zero over the relevant interval.
For practice, draw two arrows into and out of a state. Make both arrows larger while keeping them equal. The state can remain stable even though turnover increases. Then make one arrow larger and predict the direction of change.
Do not label every flat graph as equilibrium. A plateau can arise from saturation, depletion, measurement ceiling or a chosen time window. Use mechanism and design evidence to decide whether dynamic balance is the best explanation.
48. birth rate equals death+loss rate
For birth rate equals death+loss rate, identify the measured state variable and the processes that can increase or decrease it. A stable state occurs when the net change is approximately zero over the relevant interval.
For practice, draw two arrows into and out of a state. Make both arrows larger while keeping them equal. The state can remain stable even though turnover increases. Then make one arrow larger and predict the direction of change.
Do not label every flat graph as equilibrium. A plateau can arise from saturation, depletion, measurement ceiling or a chosen time window. Use mechanism and design evidence to decide whether dynamic balance is the best explanation.
49. water uptake equals loss
For water uptake equals loss, identify the measured state variable and the processes that can increase or decrease it. A stable state occurs when the net change is approximately zero over the relevant interval.
For practice, draw two arrows into and out of a state. Make both arrows larger while keeping them equal. The state can remain stable even though turnover increases. Then make one arrow larger and predict the direction of change.
Do not label every flat graph as equilibrium. A plateau can arise from saturation, depletion, measurement ceiling or a chosen time window. Use mechanism and design evidence to decide whether dynamic balance is the best explanation.
50. charge flow balance
For charge flow balance, identify the measured state variable and the processes that can increase or decrease it. A stable state occurs when the net change is approximately zero over the relevant interval.
For practice, draw two arrows into and out of a state. Make both arrows larger while keeping them equal. The state can remain stable even though turnover increases. Then make one arrow larger and predict the direction of change.
Do not label every flat graph as equilibrium. A plateau can arise from saturation, depletion, measurement ceiling or a chosen time window. Use mechanism and design evidence to decide whether dynamic balance is the best explanation.
51. force balance
For force balance, identify the measured state variable and the processes that can increase or decrease it. A stable state occurs when the net change is approximately zero over the relevant interval.
For practice, draw two arrows into and out of a state. Make both arrows larger while keeping them equal. The state can remain stable even though turnover increases. Then make one arrow larger and predict the direction of change.
Do not label every flat graph as equilibrium. A plateau can arise from saturation, depletion, measurement ceiling or a chosen time window. Use mechanism and design evidence to decide whether dynamic balance is the best explanation.
52. moment balance where context/syllabus permits
For moment balance where context/syllabus permits, identify the measured state variable and the processes that can increase or decrease it. A stable state occurs when the net change is approximately zero over the relevant interval.
For practice, draw two arrows into and out of a state. Make both arrows larger while keeping them equal. The state can remain stable even though turnover increases. Then make one arrow larger and predict the direction of change.
Do not label every flat graph as equilibrium. A plateau can arise from saturation, depletion, measurement ceiling or a chosen time window. Use mechanism and design evidence to decide whether dynamic balance is the best explanation.
53. mass balance
For mass balance, identify the measured state variable and the processes that can increase or decrease it. A stable state occurs when the net change is approximately zero over the relevant interval.
For practice, draw two arrows into and out of a state. Make both arrows larger while keeping them equal. The state can remain stable even though turnover increases. Then make one arrow larger and predict the direction of change.
Do not label every flat graph as equilibrium. A plateau can arise from saturation, depletion, measurement ceiling or a chosen time window. Use mechanism and design evidence to decide whether dynamic balance is the best explanation.
54. energy accounting
For energy accounting, identify the measured state variable and the processes that can increase or decrease it. A stable state occurs when the net change is approximately zero over the relevant interval.
For practice, draw two arrows into and out of a state. Make both arrows larger while keeping them equal. The state can remain stable even though turnover increases. Then make one arrow larger and predict the direction of change.
Do not label every flat graph as equilibrium. A plateau can arise from saturation, depletion, measurement ceiling or a chosen time window. Use mechanism and design evidence to decide whether dynamic balance is the best explanation.
55. matter accounting
For matter accounting, identify the measured state variable and the processes that can increase or decrease it. A stable state occurs when the net change is approximately zero over the relevant interval.
For practice, draw two arrows into and out of a state. Make both arrows larger while keeping them equal. The state can remain stable even though turnover increases. Then make one arrow larger and predict the direction of change.
Do not label every flat graph as equilibrium. A plateau can arise from saturation, depletion, measurement ceiling or a chosen time window. Use mechanism and design evidence to decide whether dynamic balance is the best explanation.
56. dynamic balance after disturbance
For dynamic balance after disturbance, identify the measured state variable and the processes that can increase or decrease it. A stable state occurs when the net change is approximately zero over the relevant interval.
For practice, draw two arrows into and out of a state. Make both arrows larger while keeping them equal. The state can remain stable even though turnover increases. Then make one arrow larger and predict the direction of change.
Do not label every flat graph as equilibrium. A plateau can arise from saturation, depletion, measurement ceiling or a chosen time window. Use mechanism and design evidence to decide whether dynamic balance is the best explanation.
57. recovery to steady state
For recovery to steady state, identify the measured state variable and the processes that can increase or decrease it. A stable state occurs when the net change is approximately zero over the relevant interval.
For practice, draw two arrows into and out of a state. Make both arrows larger while keeping them equal. The state can remain stable even though turnover increases. Then make one arrow larger and predict the direction of change.
Do not label every flat graph as equilibrium. A plateau can arise from saturation, depletion, measurement ceiling or a chosen time window. Use mechanism and design evidence to decide whether dynamic balance is the best explanation.
58. overshoot around set point
For overshoot around set point, identify the measured state variable and the processes that can increase or decrease it. A stable state occurs when the net change is approximately zero over the relevant interval.
For practice, draw two arrows into and out of a state. Make both arrows larger while keeping them equal. The state can remain stable even though turnover increases. Then make one arrow larger and predict the direction of change.
Do not label every flat graph as equilibrium. A plateau can arise from saturation, depletion, measurement ceiling or a chosen time window. Use mechanism and design evidence to decide whether dynamic balance is the best explanation.
59. oscillation around stable level
For oscillation around stable level, identify the measured state variable and the processes that can increase or decrease it. A stable state occurs when the net change is approximately zero over the relevant interval.
For practice, draw two arrows into and out of a state. Make both arrows larger while keeping them equal. The state can remain stable even though turnover increases. Then make one arrow larger and predict the direction of change.
Do not label every flat graph as equilibrium. A plateau can arise from saturation, depletion, measurement ceiling or a chosen time window. Use mechanism and design evidence to decide whether dynamic balance is the best explanation.
60. lag in feedback
For lag in feedback, identify the measured state variable and the processes that can increase or decrease it. A stable state occurs when the net change is approximately zero over the relevant interval.
For practice, draw two arrows into and out of a state. Make both arrows larger while keeping them equal. The state can remain stable even though turnover increases. Then make one arrow larger and predict the direction of change.
Do not label every flat graph as equilibrium. A plateau can arise from saturation, depletion, measurement ceiling or a chosen time window. Use mechanism and design evidence to decide whether dynamic balance is the best explanation.
61. baseline drift versus steady state
For baseline drift versus steady state, identify the measured state variable and the processes that can increase or decrease it. A stable state occurs when the net change is approximately zero over the relevant interval.
For practice, draw two arrows into and out of a state. Make both arrows larger while keeping them equal. The state can remain stable even though turnover increases. Then make one arrow larger and predict the direction of change.
Do not label every flat graph as equilibrium. A plateau can arise from saturation, depletion, measurement ceiling or a chosen time window. Use mechanism and design evidence to decide whether dynamic balance is the best explanation.
62. path dependence versus steady state
For path dependence versus steady state, identify the measured state variable and the processes that can increase or decrease it. A stable state occurs when the net change is approximately zero over the relevant interval.
For practice, draw two arrows into and out of a state. Make both arrows larger while keeping them equal. The state can remain stable even though turnover increases. Then make one arrow larger and predict the direction of change.
Do not label every flat graph as equilibrium. A plateau can arise from saturation, depletion, measurement ceiling or a chosen time window. Use mechanism and design evidence to decide whether dynamic balance is the best explanation.
63. interaction changes steady state
For interaction changes steady state, identify the measured state variable and the processes that can increase or decrease it. A stable state occurs when the net change is approximately zero over the relevant interval.
For practice, draw two arrows into and out of a state. Make both arrows larger while keeping them equal. The state can remain stable even though turnover increases. Then make one arrow larger and predict the direction of change.
Do not label every flat graph as equilibrium. A plateau can arise from saturation, depletion, measurement ceiling or a chosen time window. Use mechanism and design evidence to decide whether dynamic balance is the best explanation.
64. threshold changes balance
For threshold changes balance, identify the measured state variable and the processes that can increase or decrease it. A stable state occurs when the net change is approximately zero over the relevant interval.
For practice, draw two arrows into and out of a state. Make both arrows larger while keeping them equal. The state can remain stable even though turnover increases. Then make one arrow larger and predict the direction of change.
Do not label every flat graph as equilibrium. A plateau can arise from saturation, depletion, measurement ceiling or a chosen time window. Use mechanism and design evidence to decide whether dynamic balance is the best explanation.
65. limiting factor changes balance
For limiting factor changes balance, identify the measured state variable and the processes that can increase or decrease it. A stable state occurs when the net change is approximately zero over the relevant interval.
For practice, draw two arrows into and out of a state. Make both arrows larger while keeping them equal. The state can remain stable even though turnover increases. Then make one arrow larger and predict the direction of change.
Do not label every flat graph as equilibrium. A plateau can arise from saturation, depletion, measurement ceiling or a chosen time window. Use mechanism and design evidence to decide whether dynamic balance is the best explanation.
66. control group steady state
For control group steady state, identify the measured state variable and the processes that can increase or decrease it. A stable state occurs when the net change is approximately zero over the relevant interval.
For practice, draw two arrows into and out of a state. Make both arrows larger while keeping them equal. The state can remain stable even though turnover increases. Then make one arrow larger and predict the direction of change.
Do not label every flat graph as equilibrium. A plateau can arise from saturation, depletion, measurement ceiling or a chosen time window. Use mechanism and design evidence to decide whether dynamic balance is the best explanation.
67. treatment shifts steady state
For treatment shifts steady state, identify the measured state variable and the processes that can increase or decrease it. A stable state occurs when the net change is approximately zero over the relevant interval.
For practice, draw two arrows into and out of a state. Make both arrows larger while keeping them equal. The state can remain stable even though turnover increases. Then make one arrow larger and predict the direction of change.
Do not label every flat graph as equilibrium. A plateau can arise from saturation, depletion, measurement ceiling or a chosen time window. Use mechanism and design evidence to decide whether dynamic balance is the best explanation.
68. temporary transient
For temporary transient, identify the measured state variable and the processes that can increase or decrease it. A stable state occurs when the net change is approximately zero over the relevant interval.
For practice, draw two arrows into and out of a state. Make both arrows larger while keeping them equal. The state can remain stable even though turnover increases. Then make one arrow larger and predict the direction of change.
Do not label every flat graph as equilibrium. A plateau can arise from saturation, depletion, measurement ceiling or a chosen time window. Use mechanism and design evidence to decide whether dynamic balance is the best explanation.
69. long-term steady level
For long-term steady level, identify the measured state variable and the processes that can increase or decrease it. A stable state occurs when the net change is approximately zero over the relevant interval.
For practice, draw two arrows into and out of a state. Make both arrows larger while keeping them equal. The state can remain stable even though turnover increases. Then make one arrow larger and predict the direction of change.
Do not label every flat graph as equilibrium. A plateau can arise from saturation, depletion, measurement ceiling or a chosen time window. Use mechanism and design evidence to decide whether dynamic balance is the best explanation.
70. short-term equilibrium claim
For short-term equilibrium claim, identify the measured state variable and the processes that can increase or decrease it. A stable state occurs when the net change is approximately zero over the relevant interval.
For practice, draw two arrows into and out of a state. Make both arrows larger while keeping them equal. The state can remain stable even though turnover increases. Then make one arrow larger and predict the direction of change.
Do not label every flat graph as equilibrium. A plateau can arise from saturation, depletion, measurement ceiling or a chosen time window. Use mechanism and design evidence to decide whether dynamic balance is the best explanation.
71. time window too short
For time window too short, identify the measured state variable and the processes that can increase or decrease it. A stable state occurs when the net change is approximately zero over the relevant interval.
For practice, draw two arrows into and out of a state. Make both arrows larger while keeping them equal. The state can remain stable even though turnover increases. Then make one arrow larger and predict the direction of change.
Do not label every flat graph as equilibrium. A plateau can arise from saturation, depletion, measurement ceiling or a chosen time window. Use mechanism and design evidence to decide whether dynamic balance is the best explanation.
72. measurement noise around steady value
For measurement noise around steady value, identify the measured state variable and the processes that can increase or decrease it. A stable state occurs when the net change is approximately zero over the relevant interval.
For practice, draw two arrows into and out of a state. Make both arrows larger while keeping them equal. The state can remain stable even though turnover increases. Then make one arrow larger and predict the direction of change.
Do not label every flat graph as equilibrium. A plateau can arise from saturation, depletion, measurement ceiling or a chosen time window. Use mechanism and design evidence to decide whether dynamic balance is the best explanation.
73. trend around constant mean
For trend around constant mean, identify the measured state variable and the processes that can increase or decrease it. A stable state occurs when the net change is approximately zero over the relevant interval.
For practice, draw two arrows into and out of a state. Make both arrows larger while keeping them equal. The state can remain stable even though turnover increases. Then make one arrow larger and predict the direction of change.
Do not label every flat graph as equilibrium. A plateau can arise from saturation, depletion, measurement ceiling or a chosen time window. Use mechanism and design evidence to decide whether dynamic balance is the best explanation.
74. anomaly during steady state
For anomaly during steady state, identify the measured state variable and the processes that can increase or decrease it. A stable state occurs when the net change is approximately zero over the relevant interval.
For practice, draw two arrows into and out of a state. Make both arrows larger while keeping them equal. The state can remain stable even though turnover increases. Then make one arrow larger and predict the direction of change.
Do not label every flat graph as equilibrium. A plateau can arise from saturation, depletion, measurement ceiling or a chosen time window. Use mechanism and design evidence to decide whether dynamic balance is the best explanation.
75. sampling interval
For sampling interval, identify the measured state variable and the processes that can increase or decrease it. A stable state occurs when the net change is approximately zero over the relevant interval.
For practice, draw two arrows into and out of a state. Make both arrows larger while keeping them equal. The state can remain stable even though turnover increases. Then make one arrow larger and predict the direction of change.
Do not label every flat graph as equilibrium. A plateau can arise from saturation, depletion, measurement ceiling or a chosen time window. Use mechanism and design evidence to decide whether dynamic balance is the best explanation.
76. average hides fluctuations
For average hides fluctuations, identify the measured state variable and the processes that can increase or decrease it. A stable state occurs when the net change is approximately zero over the relevant interval.
For practice, draw two arrows into and out of a state. Make both arrows larger while keeping them equal. The state can remain stable even though turnover increases. Then make one arrow larger and predict the direction of change.
Do not label every flat graph as equilibrium. A plateau can arise from saturation, depletion, measurement ceiling or a chosen time window. Use mechanism and design evidence to decide whether dynamic balance is the best explanation.
77. local variation under stable whole
For local variation under stable whole, identify the measured state variable and the processes that can increase or decrease it. A stable state occurs when the net change is approximately zero over the relevant interval.
For practice, draw two arrows into and out of a state. Make both arrows larger while keeping them equal. The state can remain stable even though turnover increases. Then make one arrow larger and predict the direction of change.
Do not label every flat graph as equilibrium. A plateau can arise from saturation, depletion, measurement ceiling or a chosen time window. Use mechanism and design evidence to decide whether dynamic balance is the best explanation.
78. stable whole hides turnover
For stable whole hides turnover, identify the measured state variable and the processes that can increase or decrease it. A stable state occurs when the net change is approximately zero over the relevant interval.
For practice, draw two arrows into and out of a state. Make both arrows larger while keeping them equal. The state can remain stable even though turnover increases. Then make one arrow larger and predict the direction of change.
Do not label every flat graph as equilibrium. A plateau can arise from saturation, depletion, measurement ceiling or a chosen time window. Use mechanism and design evidence to decide whether dynamic balance is the best explanation.
79. equilibrium model assumption
For equilibrium model assumption, identify the measured state variable and the processes that can increase or decrease it. A stable state occurs when the net change is approximately zero over the relevant interval.
For practice, draw two arrows into and out of a state. Make both arrows larger while keeping them equal. The state can remain stable even though turnover increases. Then make one arrow larger and predict the direction of change.
Do not label every flat graph as equilibrium. A plateau can arise from saturation, depletion, measurement ceiling or a chosen time window. Use mechanism and design evidence to decide whether dynamic balance is the best explanation.
80. open-system steady state
For open-system steady state, identify the measured state variable and the processes that can increase or decrease it. A stable state occurs when the net change is approximately zero over the relevant interval.
For practice, draw two arrows into and out of a state. Make both arrows larger while keeping them equal. The state can remain stable even though turnover increases. Then make one arrow larger and predict the direction of change.
Do not label every flat graph as equilibrium. A plateau can arise from saturation, depletion, measurement ceiling or a chosen time window. Use mechanism and design evidence to decide whether dynamic balance is the best explanation.
81. closed-system equilibrium
For closed-system equilibrium, identify the measured state variable and the processes that can increase or decrease it. A stable state occurs when the net change is approximately zero over the relevant interval.
For practice, draw two arrows into and out of a state. Make both arrows larger while keeping them equal. The state can remain stable even though turnover increases. Then make one arrow larger and predict the direction of change.
Do not label every flat graph as equilibrium. A plateau can arise from saturation, depletion, measurement ceiling or a chosen time window. Use mechanism and design evidence to decide whether dynamic balance is the best explanation.
82. dynamic balance final rule
For dynamic balance final rule, identify the measured state variable and the processes that can increase or decrease it. A stable state occurs when the net change is approximately zero over the relevant interval.
For practice, draw two arrows into and out of a state. Make both arrows larger while keeping them equal. The state can remain stable even though turnover increases. Then make one arrow larger and predict the direction of change.
Do not label every flat graph as equilibrium. A plateau can arise from saturation, depletion, measurement ceiling or a chosen time window. Use mechanism and design evidence to decide whether dynamic balance is the best explanation.
Steady state and equilibrium are not always identical
In an open system, a quantity can remain steady because material or energy continuously enters and leaves. In a closed-system equilibrium model, opposing processes may balance without net macroscopic change. Use the terminology appropriate to the syllabus context and evidence rather than treating the labels as interchangeable everywhere.
Links
Use the Science Hub, Vol 0119 Response Lag, Vol 0123 Path Dependence, the Examination Craft hub and the PSLE Learner’s Guide.
Official-source discipline
For the current 2027 SEC G2 school-candidate framework, use the official SEAB G2 syllabus directory and linked K223–K225 Science syllabuses. Dynamic-balance reasoning is an eduKateSengkang framework for interpreting stable states, not an additional SEAB syllabus topic.
Final rule
A flat result does not automatically mean nothing is happening. Identify the opposing processes, compare their rates and decide whether stability comes from genuine balance, saturation, depletion or measurement limits.
G2 SEC Learner’s Guide: open the Vol 0001–0131 index · continue to Vol 0132–0175.
