Question

Two particles are projected simultaneously from the towers of same height as shown in the figure with velocities $V_A=20\text{m/s}$ and $V_B=10\text{m/s}$ respectively. They collide in air after 0.5 seconds. Find ${}^{\prime }{\theta }^{\prime }$. Answer in degrees

Answer 1

For the particles to collide at the end,
$(s_{\text{rel}}{)}_y=0$
$(s_{\text{rel}}{)}_y=(u_{\text{rel}}{)}_{y}t+\frac{1}{2}(a_{\text{rel}}{)}_y{t}^2$
$0=(V_A\sin \theta -V_B)t+0$ $[\because (a_{\text{rel}}{)}_y=0]$
$0=20\sin \theta -10$
$\sin \theta =\frac{1}{2}$
$\theta ={30}^{\circ }$