A child climbs a flight of stairs four times. The duration of each climb is noted. Which recorded time corresponds to the run in which the child’s useful power is highest?
- A$10\,\text{s}$
- B$20\,\text{s}$
- C$30\,\text{s}$
- D$40\,\text{s}$
Physics 0625 · IGCSE · Energy, work and power