Two particles are moving along two long straight lines, in the same plane, with the same speed $= 20 \,\,cm/s$. The angle between the two lines is $60^o$, and their intersection point is $O$. At a certain moment, the two particles are located at distances $3\,m$ and $4\,m$ from $O$, and are moving towards $O$. Subsequently, the shortest distance between them will be

A boy throws a ball with a velocity $u$ at an angle $\theta$ with the horizontal. At the same instant he starts running with uniform velocity to catch the ball before if hits the ground. To achieve this he should run with a velocity of

The equation of a projectile is $y=\sqrt{3} x-\frac{ x^2}{2}$, the velocity of projection is

A body is projected horizontally from the top of a tower with initial velocity $18\,m s^{-1}$. It hits the ground at angle $45^o$. What is the vertical component of velocity when it strikes the ground ......... $ms^{-1}$

Suppose a player hits several baseballs. Which baseball will be in the air for the longest 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