A projectile is thrown with speed $40 \,ms ^{-1}$ at angle $\theta$ from horizontal. It is found that projectile is at same height at $1 \,s$ and $3 \,s$. What is the angle of projection?
$\tan ^{-1}\left(\frac{1}{\sqrt{2}}\right)$
$\tan ^{-1}\left(\frac{1}{\sqrt{3}}\right)$
$\tan ^{-1}(\sqrt{3})$
$\tan ^{-1}(\sqrt{2})$
Which of the following sets of factors will affect the horizontal distance covered by an athlete in a long-jump event
A grasshopper can jump maximum distance $1.6\; m$. It negligible time of the ground. How far can it go in $10 \;s$?
A ball is projected upwards from the top of tower with a velocity $50\,\,m{s^{ - 1}}$ making an angle ${30^o}$ with the horizontal. The height of tower is $ 70 \,m$. After how many seconds from the instant of throwing will the ball reach the ground ........ $\sec$
A shell fired from the base of a mountain just clears it. If $\alpha$ is the angle of projection then the angular elevation of the summit $\beta$ is
The range of a particle when launched at an angle of ${15^o}$ with the horizontal is $1.5 \,km$. What is the range of the projectile when launched at an angle of ${45^o}$ to the horizontal ........ $km$