Question

A ball is thrown up vertically with a velocity of 20 ms-¹. At what height will its kinetic energy be half its original volume?
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Answer 1

Given :

A ball is thrown vertically upward at a velocity of 20 m/s

To Find :

Height at which kinetic energy of ball be half.

Solution :

★ Let a body is thrown vertically upward at a speed of 20 m/s from point A and B be the point where kinetic energy of ball be half.

Kinetic energy at point A :

➛ K = 1/2 mu²

➛ K = 1/2 m (20)²

➛ K = 400m/2

➛ K = 200m

where m is the mass of ball.

Potential energy at point B :

Let h be the height at where kinetic energy of ball be half$.$

➛ U = mgH

Kinetic energy at point B :

➛ K' = K/2

➛ K' = 200m/2

➛ K' = 100m

By applying concept of mechanical energy conservation :-

➠ K = U + K'

➠ 200m = mgH + 100m

➠ 200 = gH + 100

➠ gH = 100

➠ H = 100/10

➠ H = 10 m

Answer 2

apply concept of energy conservation.

k1 + u1 = k2 + u2

200m + 0 = 100m + mgH

100 = 10H

H = 10m

hope it helps :)