# Why is WR for 4x100m relay less than 4 times WR for 100m sprint.

by glb_lub
Tags: 100m, sprint, times
 P: 20 Hello, The 2012 London Olympics concluded a day or two ago. We saw that a few records were broken in athletics. In particular, the 4x100m men's relay record. Currently the WR are as follows :- 1) 100m Men's sprint - 9.58 s 2) 200m Men's sprint - 19.19s 3) 4x100m Men's relay - 36.84s The world's fastest man Usain Bolt features in all the races. Thus in the relay the 4 athletes are either as fast as Bolt(i.e Bolt himself) or slower. Now if one observes the record time for relay, it is 36.84s , which is less than 4 times the 100m sprint record. Whereas the record time for 200m is more than twice the 100m sprint record. I think I understand why it is so for 200m sprint (it is relatively easier to sustain high speeds for smaller bursts ) . But I am unable to explain the 4x100m relay case in a succinct way. Each athlete runs 100m in the 4x100m sprint. But only the first runner has to start at the sound of gun fire. Whereas for the other 3 runners, there is a 20m changeover box,during which the baton changes hands. So I guess, the acceleration time and deceleration time for 1st and 2nd runner overlap partially (similarly for 2nd and 3rd , etc). I guess my explanation has loopholes and would like to know more about this issue.
 PF Patron P: 919 Since the total time does not include the acceleration of the 3 last runners (the baton gets a "running start" with those runners, so to speak) it is not surprising that the total time is less than 4 x 100m. Even assuming that runners cannot run at their maximum speed when they pass the baton there will be much time saved. For the 400 m relay to compare to 4 x 100 m the next runner would have to wait in his start block and only start accelerating when the baton is in his hand - then you'd see total times >= 4 x 100 m.
P: 20
 Quote by Filip Larsen Since the total time does not include the acceleration of the 3 last runners (the baton gets a "running start" with those runners, so to speak) it is not surprising that the total time is less than 4 x 100m. Even assuming that runners cannot run at their maximum speed when they pass the baton there will be much time saved. For the 400 m relay to compare to 4 x 100 m the next runner would have to wait in his start block and only start accelerating when the baton is in his hand - then you'd see total times >= 4 x 100 m.
Thanks. That was nicely put.

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