Question

What is the average velocity of a particle projected from the ground with speed u at an angle $\alpha$ with the horizontal over a time interval from beginning till it strikes the ground again?

Answer 1

Let the time of flight be $T$

From figure $u_x=ucos\alpha$

$\therefore$ Total displacement of the particle $S=u_{x}T=\left(ucos\alpha \right)T$

$\therefore$ Average velocity $v_{avg}=\frac{S}{T}=u$ $cos\alpha$