Question

A boy of mass 60 kg jumps from a height of 5 m on a trampoline, and bounces back successfully. What is the maximum kinetic energy that the boy will achieve?

• A. 6 kJ
• B. 3 kJ
• C. 2.5 kJ
• D. 5 kJ

Answer 1

The correct option is B 3 kJ

Consider the boy, the ground, and the trampoline as a system. The mechanical energy of this system is conserved. The trampoline will have the maximum potential energy when all the gravitational potential energy of the boy converts into the potential energy of the trampoline.

Maximum kinetic energy= Gravitational potential energy
Maximum kinetic energy= mgh
Maximum kinetic energy$=60105=3000J=3kJ$