If a DeLorean rolls gently (vo = 0) off a vertical cliff, how long does it take it to reach a downward velocity of 78 km/h?

Answer 1

V = 78km/h = 78000m/3600s = 21.67 m/s.

d=(V^2-Vo^2)/2g=(469.5-0)/19.6=23.95 m.

t = (V-Vo)/g = (21.67-0)/9.8 = 2.21 s.

Answer 2

NOTE: The 2nd step(d) is not needed.