A car starts from rest and travels for 5.0s with a uniform acceleration of +1.5 m/s^2. The driver then applies the brakes, causing a uniform acceleration of -2.0 m/s^2. If the brakes are applied for 3.0 s, how fast is the car going at the end of the braking period, and how far has it gone from its start?

Answer 1

1) find the velocity at the time brakes were applied: Vf=at=7.5m/s

2) then find the final velocity at end of brakeing: Vf=7.5-2*t
1.5 m/s

Answer 2

20m