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 potential energy is assumed to be zero at the ground. Consider g = 10 $m/s^2$ and assume that there is no loss of energy.


Choose the correct statement for the situation where both boys move towards each other.

[1 mark]

• A. A will lose potential energy, and B will gain potential energy.
• B. B will lose potential energy, and A will gain potential energy.
• C. Both will gain potential energy.
• D. Both will lose potential energy.

Answer 1

The correct option is B B will lose potential energy, and A will gain potential energy.

Potential energy is assumed to be zero at the ground. As A will move up the stairs towards B, the vertical distance between the ground and A will increase. Hence, the potential energy of A with respect to the ground will increase as well.

B will move down the stairs towards A. Therefore, the potential energy of B with respect to the ground will decrease.