Question

A body is projected up with a velocity $30m/s$ at an angle ${30}^o$ with the horizontal.what will the angle with horizontal be after 1.5 sec? [Take $g=10m/s^2]$.

• A. $\theta ={10}^{\circ }$
• B. $\theta =0^{\circ }$
• C. $\theta ={45}^{\circ }$
• D. $\theta ={40}^{\circ }$

Answer 1

Answer: (B)

$\theta =0^{\circ }$

Given,

$u=30m/s$

$\theta ={30}^0$

$g=10m/s^2$

Time of flight, $T=\frac{2usin\theta }{g}$

$T=\frac{2\times 30\times sin{30}^0}{10}$

$T=3sec$

After $3sec$, projectile is at the peak, and the angle with horizontal is $0^0$.

The correct option is B.