Question

A driver of a car slows to a stop. The decrease in speed is constant. When the driver first applies the brakes, the car is going 50mi/h. After 5 s the car is traveling 30mi/h. About how long does it take the car to stop?

Answer 1

Acceleration = (v1-v0)/t = (30-50)/5=-20 mph/s
Additional time it takes to stop
=(0-30)/-20
=1.5 seconds
Total time = 5+1.5 =6.5 seconds.