Question

Two boys A and B are standing at two positions as shown in the diagram. Each step is 20 cm high and 20 cm wide. The mass of the ball is 300 grams, The potential energy is assumed to be zero at the ground. Consider $g=10m/s^2$ and assume that there is no loss of energy.

What is the potential energy (in Joules) of the ball at the point of release?

• A. 6.3

Answer 1

The correct option is A 6.3
The height of each step is 20 cm and the boy is on 8th step hold ball in hand which is 50cm above from the 8th step.
So, total height = 20 x 8 + 50 = 210 cm = 2.1 m

Given mass (m) = 300 grams = 0.3 kg
Potential energy = mgh = 0.3 x 10 x 2.1 = 6.3 J