A projectile is thrown in the upward direction making an angle of $60^o$ with the horizontal direction with a velocity of $150\, ms^{-1}$. Then the time after which its inclination with the horizontal is $45^o$ is
$15\,\left( {\sqrt 3 - 1} \right)\,s$
$15\,\left( {\sqrt 3 + 1} \right)\,s$
$7.5\,\left( {\sqrt 3 - 1} \right)\,s$
$7.5\,\left( {\sqrt 3 + 1} \right)\,s$
For a projectile, the ratio of maximum height reached to the square of flight time is ($g = 10 ms^{-2}$)
Ratio between maximum range and square of time of flight in projectile motion is
A projectile is thrown at an angle $\theta$ such that it is just able to cross a vertical wall at its highest point as shown in the figure.The angle $\theta$ at which the projectile is thrown is given by
If at any point on the path of a projectile its velocity is $u$ at inclination $\alpha$ then it will move at right angles to former direction after time
A particle $A$ is projected vertically upwards. Another identical particle $B$ is projected at an angle of $45^o $ . Both reach the same height. The ratio of the initial kinetic energy of $A$ to that of $B$ is