Question

A driver traveling at a speed of 21 m/s tops a hill and spots a deer standing in the middle of the road 90 meters away. He hits the brakes and panic stops the car in 8 seconds. How far did the car travel before stopping?

Answer 1

The car would have travelled 84 metres just missing the deer.

Explanation:

We first of all need to determine the rate of deceleration of the car using the equation:
`v=u+at`
Where `v=0` is the final velocity, `u=21` is the initial velocity, `a` is the acceleration and `t=8` is the time. Therefore:
`0=21+a8`, `a=-21/8=-2.625`m/s

The distance can be found using the equation:
`s=ut+1/2at^2`
Substituting values gives:
`s=21*8-1/2*21/8*8^2=21*8-21*4=84`m/s