Question

A train travelling at 20 m/s stops in 40 seconds. What is the acceleration of the train (numeric answers only - no units)

Answer 1

The equation of motion we will use is

`v=u+at`

Where

v is the final velocity

u is the initial velocity

a is the acceleration

t is the time

From the problem, we can figure out that the starting velocity, u, is 20. The time, t, is 40. The final velocity, v, will be 0.

Substituting, let's figure out acceleration, a :

`\begin{gathered} v=u+at \\ 0=20+a(40) \\ 0=20+40a \\ 40a=-20 \\ a=-(20)/(40) \\ a=-(0.5m)/(s^2) \end{gathered}`

The acceleration is negative because it is deceleration.