A sprinter of mass starts a race on a horizontal track
PHYSICS · Multi-part · CBSE · Physics · Work, Energy and Power · Work, Energy and Power
Problem
A sprinter of mass 70kg starts a race on a horizontal track. For the first 2.0s he pushes backward on the ground with a constant horizontal force of 350N; thereafter the force drops to nearly zero as he coasts.
(i) Using suitable definitions, distinguish between average power and instantaneous power for the sprinter during the first 2.0s.
(ii) Assuming the force is the only horizontal force acting, find the sprinter’s speed at t=0.80s after the start.
(iii) Determine the instantaneous power developed at t=0.80s.
(iv) Calculate the average power developed over the entire 2.0s push phase.
(v) Give a reasoned comparison of the values obtained in parts (iii) and (iv), stating which is larger and why.