Question

From what height would a compact car have to be dropped to have the same kinetic energy that it has when being driven at 100 km/h?

Answer 1

Answer: 39.32746882 meters.

How: KE = 1/2massxvelocity^2 = massxheightxaccelerationofGravity.

Your velocity is 100km/h = 27.777..., so:
1/2(27.777...)^2 x mass = (385.8024691 m^2/s^2)xmass.

(385.8024691m^2/s^2)m = mh(9.81m/s^2).

Mass and all units except meters cancel when you solve for height, h, which is the answer I gave above.

Answer 2

100 km/h = 27.78 m/s

V = sqrt (2gH)
H = V^2/(2g) = 39.3 m

I agree with the previous answer, except for the excessive number of significant figures. No more than three are justified