In projectile motion, the modulus of rate of change of velocity

A cricket ball is thrown at a speed of $28\; m /s$ in a direction $30^o$ above the horizontal. Calculate

$(a)$ the maximum height,

$(b)$ the time taken by the ball to return to the same level, and

$(c)$ the distance from the thrower to the point where the ball returns to the same level

The maximum horizontal range of a projectile is $160\, m$. When the projectile is thrown  with the same speed at an elevation of $30^o$ from the horizontal, it will reach to the  maximum height of   ……… $m$

A body is thrown at angle $30^{\circ}$ to the horizontal with the velocity of $30\; m / s$. After $1\;sec$, its velocity will be (in $m/s$) $\left(g=10\; m / s ^{2}\right)$

Two objects are projected with same velocity ' $u$ ' however at different angles $\alpha$ and $\beta$ with the horizontal. If $\alpha+\beta=90^{\circ}$, the ratio of horizontal range of the first object to the $2^{\text {nd }}$ object will be :