Gravity with a car moving at constant speed?

Question

Constant speed always throws me off

A sports car moving at constant speed travels 100 m in 5.3s. If it then brakes and comes to a stop in 4.0s, what is its acceleration? Express the answer in terms of g's, where g = 9.80 m/s^2

Answer 1

First use the definition of velocity:

velocity = distance / time = 100m/5.3s = ?

Then the definition of acceleration:

acceleration = (change in velocity) / time

Divide that answer by 9.80 m/s^2, and you'll have your answer.