A train with a constant velocity of + 28.6 m/s approaches a small town. the operator applies the brake, reducing the train's velocity to + 11.4 m/s. if the average acceleration of the train during braking is 1.35 m/s2, for what elapsed time does the operator apply the brake?

Question

Asa Barrera

Physics

29 May, 05:13

A train with a constant velocity of + 28.6 m/s approaches a small town. the operator applies the brake, reducing the train's velocity to + 11.4 m/s. if the average acceleration of the train during braking is 1.35 m/s2, for what elapsed time does the operator apply the brake?

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Answers (1)

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Madelyn Reid · Answer 1

We shall use the formula

v = u + at

where

v = final velocity

u = intal velocity

t = time

a = acceleration

For the given problem,

v = 11.4 m/s (final elocity)

u = 28.6 m/s (initial velocity)

a = - 1.35 m/s^2 (negative acceleration for braking)

Therefore

11.4 = 28.6 - 1.35t

1.35t = 28.6 - 11.4 = 17.2

t = 17.2/1.35 = 12.7407 s

Answer: 12.74 s