Question

body of mass 20 kg is initially at a height of 3 m above the ground . It is lifted to a height of 2 m 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 (Answer)

Answer 2

Given:

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

To find:

Increase in potential energy?

Solution:

• Let potential energy be denoted as PE.

Initial PE :

$PE_{i} = mgh$

$\implies PE_{i} = 20 \times 10 \times 3$

$\implies PE_{i} = 600 \: joule$

Final PE :

$PE_{f} = mgh$

$\implies PE_{f} = 20 \times 10 \times (3 + 2)$

$\implies PE_{f} = 20 \times 10 \times 5$

$\implies PE_{f} = 1000 \: joule$

So, increase in PE will be :∆PE = 1000 - 600 = 400 Joules