Question

A motorcyclist sees a branch in the road and hits the brakes, slowing down at -6.42 m/s. if it takes him 2.85 seconds to stop, what was his starting velocity?

Answer 1

Use the definition of average acceleration:

a = ∆v / t

If v is the starting speed, then ∆v = 0 - v, so solve for v :

-6.42 m/s² = (0 - v) / (2.85 s)

v = (6.42 m/s²) (2.85 s)

v ≈ 18.3 m/s