Question

A sprinter starting to run from rest, reaches a speed of 8m/s in 2 second, what is the average power needed to accelerate like this ?​

Answer 1

Answer:

okay

Explanation:

power is rate of doing work

power is workdone over time taken

but you don't have information concerning the force

Answer 2

Power = work/time

Work = force x distance

Force = mass x acceleration

So Power = (mass x acceleration x distance) / (time)

acceleration = 8m/s / 2sec  =  4 m/s²

distance = (avg speed) x (time) = 8 m

time = 2 sec

we don't know the runner's mass

Power = (mass) x (4 m/s²) x (8 m) / (2 sec)

Power = (16 x mass in kg) watts

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Slightly easier way to do it:

Power = (runner's kinetic energy at the end) / (time)

Power = (1/2 m v²) / (time)

Power = (1/2 mass) (64 m²/s²) / (2 sec)

Power = (16 x runner's mass in kg) watts