College Physics with MasteringPhysics 7th Edition by Jerry Wilson,Anthony Buffa,Bo Lou

Exercise 69

A sprinter of mass 65.0 kg starts his race by pushing horizontally backward on the starting blocks with a force of 200 N. (a) What force causes him to accelerate out of the blocks: (1) his push on the blocks; (2) the downward force of gravity; or (3) the force the blocks exert forward on him (b) Determine his initial acceleration as he leaves the blocks.