Question

A boy fall from a height ' h' on to a pit filled with sand his legs plungs into the sand to a depth 'd' what is the velocity attained by the boy when he just reaches sand?'

Answer 1

$\\ \\ \textbf{K.E = P.E} \: ( \textbf{Law of conservation of energy}) \\ \\ \textbf{K.E} = \bold{m \times g \times h} \\ \\ \bold{\frac {1}{2} m{v}^{2}} = \textbf{mgh} \\ \\ \bold{{v}^{2}} = \bold{2gh} \\ \\ \textbf{v} = \bold{\red{\sqrt{2gh}}}$