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
$\frac{u}{g \cos ec \alpha}$
$\frac{u}{g \sin \alpha}$
$\frac{u}{g \cos \alpha}$
$\frac{u}{g \sec \alpha}$
If a stone is to hit at a point which is at a distance $d$ away and at a height $h$ above the point from where the stone starts, then what is the value of initial speed $u$ if the stone is launched at an angle $\theta $ ?
A missile is fired for maximum range at your town from a place $100\, km$ away from you. If the missile is first detected at its half way point, how much warning time will you have ? (Take $g = 10\, m/s ^2$) the maximum height of the missile is
A boy playing on the roof of a $10\, m$ high building throws a ball with a speed of $10\, m/s$ at an angle $30^o$ with the horizontal. ........ $m$ far from the throwing point will the ball be at the height of $10\, m$ from the ground . $(g \,= \,10 m/s^2, \,sin \,30^o \,= \,\frac{1}{2}$, $\cos \,{30^o}\, = \,\frac{{\sqrt 3 }}{2}$)
For a given angle of the projectile if the initial velocity is doubled the range of the projectile becomes
A stone is projected from the ground with velocity $50 \,m/s$ at an angle of ${30^o}$. It crosses a wall after $3$ sec. How far beyond the wall the stone will strike the ground .......... $m$ $(g = 10\,m/{\sec ^2})$