$(a)$ An arrow moves forward when released from a stretched bow. Explain the transformation of energy in the process.
$(b)$ $A$ boy of mass $50 \, kg$ climbs up a vertical height of $100 \, m$. Calculate the amount of potential energy he gains.

(N/A) When the bow is stretched,it stores elastic potential energy. When the arrow is released,this stored potential energy is transformed into the kinetic energy of the arrow,causing it to move forward.
$(b)$ Given:
Mass $(m) = 50 \, kg$
Height $(h) = 100 \, m$
Acceleration due to gravity $(g) = 10 \, m/s^2$
Potential Energy $(PE) = m \times g \times h$
$PE = 50 \times 10 \times 100$
$PE = 50,000 \, J$ or $50 \, kJ$.