Question

A ball is thrown vertically upwards with a velocity of 20m/s. At what height, will its kinetic energy be half its original value?

(a) 10.20m

(b) 10m

(c) 15m

(d) 5m

I have been asked this question in quiz.

The query is from Collision and Friction in section Nature of Physical World of Engineering Physics I

Answer 1

Correct choice is (a) 10.20m

The explanation: Work done against gravitation = Change in kinetic energy

mgh = 1/2 mv^2-1/2×1/2 mv^2

h = v^2/4g= 10.20m.