Its total energy just before hitting the ground is?

A ball of mass 0.1kg is thrown vertically upwards with a speed of 10ms-1 from the top of a tower 10m high. Neglecting air resistance, its total energy just before hitting the ground is (take g = 10ms-2)

A. 5 J
B. 10 J
C. 15 J
D. 20 J

Correct Answer: Option A

Explanation

Height h = 1/2 (U²/g) = 10²/20 = 5m

Energy before hitting ground is = P.E at the height of 5m.

P.E = mgh = 0.1 x 10 x 5 = 5 J