An Olympic athlete of mass 80kg competes in a 100m race. What is the best estimate of his mean kinetic energy during the race?

Question

anonymous · Answer

taking the average velocity of a 100m olympic athlete wich is 10m/s1. It would be around 400J.

kropot72 · Answer

$$K=\frac{1}{2}mv ^{2}$$
where K is the energy in joules, m is the mass in kg and v is the speed in meters/sec.
The athlete can be assumed to run 100m in 10 seconds giving v = 10 m/s.
$$K=\frac{80\times 10^{2}}{2}$$

anonymous · Answer

Sry my mistake the answer is 4000J

kropot72 · Answer

@benjakkals 4000J is correct.

anonymous · Answer

how  do you know it's 10m/s ??

kropot72 · Answer

@1234abdc The question asks for an estimate. Checking on Olympic results shows that a good time for the 100m is 10 seconds. This gives an average speed of 10 m/s.

anonymous · Answer

so it's general knowledge .. okay thanks