Question

A 75-kg long-jumper takes 3.1 s to reach a prejump speed of 10 m/s. what is his power output?

Answer 1

For this first we need to calculate acceleration of the jumper i.e, a = v/t = 10m/s / 3.1 s now we need to calculate the force of the jumper i.e, f = m * a = 75 * 10/3.1 now we need to calculate the power output for that the formula is power output = force * velocity = 75 * (10 / 3.1) * 3.1 = 75 *10 = 750

Answer 2

The equation for Power is:

Power = Work / time

According to work energy theorem, the work done is equal to the change in kinetic energy, therefore:

P = [KE(f) – KE(i)] / t

Since the jumper starts from rest, so KE(i) is zero, hence:

P = KE(f) / t

Where KE kinetic energy is 0.5 mv^2, therefore:

P = 0.5 mv^2 / t

P = 0.5 (75 kg) (10 m/s)^2 / 3.1 s

P = 1209.68 W