Question

A catapult throws a stone of mass 0.10 kg with a velocity of 30 ms⁻¹. If 25% of the P.E. of the elastic band is wasted during transmission, find the magnitude of the potential energy.

Answer 1

The stone’s kinetic energy is:

\[ \text{K.E.} = \frac{1}{2}\, mv^{2} \]

\[= \frac{1}{2} \times 0.10 \times 30^{2} \]

= 45 J

Since 25% of the elastic band’s potential energy is wasted, only 75% is transferred to the stone.

Let the original potential energy be (U).

0.75U = 45

\[U = \frac{45}{0.75}\]

U = 60 J

Therefore, the potential energy of the elastic band is 60 J.