(a) In 2009, Usain Bolt ran the last 100 meters of the 150-meter race in 8.70 seconds. What is Usain

Question

Bolt’s speed?
(b) The world record for the 100-meter dash is 9.58 seconds (Bolt, 2009). Use the speed from part (a)
as his maximum velocity. Assume a sprinter accelerates at a constant rate up to their maximum
velocity, which is maintained for the remainder of the race, no matter how long it is. What is the
duration of the acceleration period at the beginning of the race?
(c) Determine the initial average acceleration in part (b).
(d) The record for the 200-meter dash is 19.19 seconds (Bolt, 2009), the 400-meter run is 43.18 seconds
(Johnson, 1999), the 800-meter run is 101.01 seconds (Rudisha, 2010), and for the 1500-meter run
it is 206.00 seconds (Guerrouj, 1998). Are these times consistent with the assumptions made?

Answer 1

9.58

Answer 2

9.58 sec.