A $100\, g$ iron ball having velocity $10 \,m/s$ collides with a wall at an angle $30^°$ and rebounds with the same angle. If the period of contact between the ball and wall is $0.1\, second$, then the force experienced by the wall is  ........... $N$

A ball is moving with speed $20 \,m / s$ collides with a smooth surface as shown in figure. The magnitude of change in velocity of the ball will be ........... $m/s$

$A$ boy hits $a$ baseball with $a$ bat and imparts an impulse $J$ to the ball. The boy hits the ball again with the same force, except that the ball and the bat are in contact for twice the amount of time as in the first hit. The new impulse equals:

$100$ balls each of mass moving with speed $v$ simultaneously strike a wall normally and reflected back with same speed, in time $t s$. The total force exerted by the balls on the wall is

In a tug-of-war contest, two men pull on a horizontal rope from opposite sides. The winner will be the man who

Figures $(a), (b), (c)$ and $(d)$ show variation of force with time.

The impulse is highest in figure.