If impulse $I$ varies with time $t$ as $I \text{ (kg m s}^{-1}) = 20 t^2 - 40 t$. The change in momentum is minimum at ........... $s$.

$A$ bullet of $4 \, g$ mass is fired from a gun of mass $4 \, kg$. If the bullet moves with the muzzle speed of $50 \, ms^{-1}$,the impulse imparted to the gun and the velocity of recoil of the gun are:

In the figure shown,a balloon is pressed against a wall. It is in equilibrium and maximum compressed state. $\vec F_1 =$ force of balloon on hand of man; $\vec F_2 =$ force of balloon on wall; $\vec F_3 =$ friction; $\vec F_4 =$ weight of balloon. Choose the correct statement.

The $F-t$ graph for an object is shown in the figure. What will be the magnitude of the change in momentum $(\Delta p)$ in the interval of $0.03\, s$ from the start?

If a force of $250\, N$ acts on a body,the momentum acquired is $125\, kg \cdot m/s$. What is the period for which the force acts on the body? ......... $s$

$A$ large number $(n)$ of identical beads,each of mass $m$ and radius $r$,are strung on a thin smooth rigid horizontal rod of length $L$ $(L >> r)$ and are at rest at random positions. The rod is mounted between two rigid supports. If one of the beads is now given a speed $v$,the average force experienced by each support after a long time is (assume all collisions are elastic):