Question

A speeding train slams on the brakes when it sees a car is on the tracks in front of it. It takes the train 25 seconds for it to go from an initial speed of 75 m/s to come to a complete stop. What is the train’s acceleration?

Answer 1

Explanation:

Given:

Initial Velocity is 75 m/s

Fianl Velocity: 0 m/s

Time 25 seconds.

Acclereation?

Use kinematic equation,

$v _{f} = v _{i} + at$

$0 = 75 \frac{m}{s} + a(3s)$

${ - 75} \frac{m}{s} = 3s(a)$

$- {25} \frac{m}{ {s}^{2} } = a$

So the acclereation is -25 m/s^2. Since the Velocity is positive and acclereation is negative, the train will be slowing down.