Question

If a car rolls gently(vo=0) off a vertical cliff, how long does it take to reach 85km/h?

Answer 1

Convert velocity to m/s:
85km*1000 m/km * 1/3600 hr/s=23.61m/s.

V = 9.8 m/s^2 * t,
23.61 m/s = 9.8 m/s^2 * t,
Solve for t:
t = 23.61 / 9.8 = 2.41 s.

Answer 2

2.4 seconds