Question

A body of mass 20kg is initially at a height of 3m above the ground. It is lifted to a height of 2m from that position. Its increase in potential energy is

Answer 1

Mass, m = 20kg

Height m, H = 3m

Potential Energy, (PE₁) = mgH

PE₁ = 20 x 9.8 x 3

PE₁ = 588 joules

Now Height (h) is 5m (3m + 2m)

(PE₂) = mgh

(PE₂) = 20 x 9.8 x 5

(PE₂) = 980 Joules

Increase in Potential Energy = PE₂ - PE₁

= 980 - 588

= 392 joules