Alisha Guglani answered this
Pleasw find answer below:-
(a) This can be solved using energy conservation, ignoring any potential outside forces, i.e. considering only the effect of the force of gravity on the child, as well as potential sources of energy loss (e.g. sound).
Initially, as the child's feet leave the trampoline, she possesses only kinetic energy, given by
The final kinetic energy of the child, the energy she possesses at her maximum altitude, is zero, as is her initial gravitational potential energy.
(b) 1/2 mv2=mgh
i.e. 1/2 v2=gh
Height at point B =11.25 m.