A projectile is thrown with velocity $U=20\ m/s ± 5\%$ at an angle $60^o.$ If the projectile falls back on the ground at the same level then    ......... $m$ of following can not be a possible answer for range.

A projectile is projected with kinetic energy $K$. If it has the maximum possible horizontal range, then its kinetic energy at the highest point will be ......... $K$

The height $y$ and the distance $x$ along the horizontal plane of a projectile on a certain planet (with no surrounding atmosphere) are given by $y = (8t - 5{t^2})$ meter and $x = 6t\, meter$, where $t$ is in second. The velocity with which the projectile is projected is ......... $m/sec$.

A cricketer can throw a ball to a maximum horizontal distance of $100 \,m$. With the same effort, he throws the ball vertically upwards. The maximum height attained by the ball is  ......... $m$

If the initial velocity of a projectile be doubled, keeping the angle of projection same, the maximum height reached by it will

Two bodies are projected with the same velocity. If one is projected at an angle of ${30^o}$ and the other at an angle of ${60^o}$ to the horizontal, the ratio of the maximum heights reached is