A cyclist of total mass 80 kg accelerates from rest to 10 m/s in 4 seconds. What is the average power output of the cyclist over this interval?
Answer and explanation
Correct answer: C. 1000 W
- Step 1: Kinetic energy gained E_k = 0.5 m v^2 = 0.5 80 10^2 = 0.5 80 100 = 4000 J. Step 2. Power is work done per unit time: P = delta E / t = 4000 J / 4 s = 1000 W (1 kW). Answer: 1000 W. Why not the others: 4000 W is energy in Joules, not power in Watts.
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