An athlete climbs a vertical rope of a constant height four times. The time taken for each climb is recorded. Which time is measured when the athlete's useful power is greatest?
12 s12\text{ s}12 s
15 s15\text{ s}15 s
18 s18\text{ s}18 s
24 s24\text{ s}24 s
95 exam-style questions on CIE IGCSE Physics 1.7.4 Power. Each one has a worked solution and a mark scheme showing where the marks go.