College Physics
11th Edition
ISBN: 9781305952300
Author: Raymond A. Serway, Chris Vuille
Publisher: Cengage Learning
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During an Olympic 100-m sprint race, Usain Bolt, the world record holder in that race, quickly accelerates to his top speed of 12.4 m/s. Analysis of his technique has shown that each of his feet makes contact with the ground for 0.0800 s, exerting a force of magnitude 2.80 ✕ 103 N during this contact. This allows the 94.0 kg Bolt to leap forward and remain airborne for 0.120 s until the next foot touches the ground. (Ignore air resistance.)
a) What are the magnitudes of the horizontal and vertical components of the force (in N) Bolt's feet exert on the ground? (Round your answers to at least three significant figures.)
Horizontal =
Vertical =
b) Assuming that the sprinter accelerates at a constant rate while his feet are in contact with the ground and does not slow down when he is airborne, by what amount does Bolt's horizontal speed (in m/s) increase with each step? (Round your answer to at least three significant figures.)
c) Assuming that the sprinter's speed increases at a constant rate by the amount found in part (b) during the 0.0800 s of contact with the ground, and remains constant for the 0.120 s he is in the air, what is the time interval (in s) required for Bolt to reach his top speed?
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