Question

An object is launched at a velocity of $20m/s$ in a direction making an angle of ${30}^{\circ }$ upward with the horizontal. What is the total flight time (between launch and touching the ground) of the object?
(Take $g=10m/s^2$)

• A. $20\sqrt{3}s$
• B. $5s$
• C. $2s$
• D. $1s$

Answer 1

The correct option is C $2s$

Time of flight for a projectile thrown at an angle $\theta$ is given by,
$T=\frac{2u\sin \theta }{g}$
Here $u=20m/s,$ $\theta ={30}^{\circ }$
$\Rightarrow T=\frac{2\times 20\sin {30}^{\circ }}{10}=2s$