Question

A ball of mass $200$ g is projected with a velocity of 30$m/s$ at ${30}^{\circ }$ from horizontal. Using the concept of impulse, find change in velocity in $2$ s. Take $g=10m/s^2$

Answer 1

Impulse will be provided by gravity and in the direction of this force that is $downward.$

impulse will be $\Delta P$ given by $\Delta P=F\Delta t=mg\times 2sec=0.2kg\times 10m/s^2\times 2sec=4N-s$

This impulse is nothing but change in $momentum.$

so change in velocity will be $\Delta v=\frac{\Delta P}{m}=\frac{4}{0.2}=20m/s$ in $downward$ direction.