A 70.0 kg sprinter starts a race with an acceleration of 2.00 m/s2. If the sprinter accelerates at that rate for 29 m, and then maintains that velocity for the remainder of the 100 m dash, what will be his time (in s) for the race?

Question

Taryn

Physics

6 June, 23:17

A 70.0 kg sprinter starts a race with an acceleration of 2.00 m/s2. If the sprinter accelerates at that rate for 29 m, and then maintains that velocity for the remainder of the 100 m dash, what will be his time (in s) for the race?

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Answers (1)

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Eva Lyons · Answer 1

t = 12.82s

Explanation:

F = m*a

= (70) * (2)

= 140 N

during the acceleration, the sprinter cover d = 29 m with time:

d = 1/2*at

29 = 1/2 * (2) * t^2

t^2 = 29s

t = 5.39s

and attains the velocity of:

v = a*t

= 2*5.39

= 10.77 m/s

Then, to cover the last x = 80 m with a speed of 10.77 m/s in time:

t = x/v

= 80/10.77

= 7.43s

Therefore, it will take the sprinter 7.43 + 5.39 = 12.82s