Question

If a boy (m = 50kg) at rest on skates is pushed by another boy who exerts a force of 200 N on him and if the first boy's final velocity is 8 m/s, what was the contact time?

Answer 1

\[\color{green}{\vec{F} \Delta t = m \Delta \vec{v} \\ \Delta t = \dfrac{400~\text{kg m/s}}{200~\text{kgm/s}^2}\\ \Delta t = 2~s}\]