Question

A car, traveling at 20 meters per second, slams on its brakes to avoid an accident. The car stops after traveling 40 meters. What was the magnitude and direction of the car’s acceleration?

Answer 1

Explanation:

Given information

u=initial velocity=20m/s

s=distance travelled=40m

v=final velocity=0m/s (the car stopped after traveling 40 m)

To find a = acceleration of the car

and its direction

We know that the equation for uniform motion is

v^2=u^2+2as

therefore by rearranging we get

a=
`(v^2 - u^2)/ 2s`

putting the values we get

a= (0 -
`20^(2)` )/
`/ 2*40`

a= -400/80

a=-5
`m/s^2`

here negative sign before 5 indicates that the acceleration direction was opposite the car's motion, hence stopping it eventually.

And the magnitude of the acceleration is 5
`m/s^2`