The force-time $(F-t)$ curve of a particle executing linear motion is as shown in the figure. The momentum acquired by the particle in the time interval from $0$ to $8 \ s$ will be ........... $N-s$.

An object with a mass $10 \, kg$ moves at a constant velocity of $10 \, m/s$. $A$ constant force then acts for $4 \, s$ on the object and gives it a speed of $2 \, m/s$ in the opposite direction. The impulse acting on the object is ......... $N \cdot s$.

What is linear momentum? Write its $SI$ unit.

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

$A$ ball of mass $3 \ kg$ strikes a wall with a velocity of $10 \ m/s$ at an angle of $30^\circ$ with the normal to the wall and rebounds at the same angle and speed. What is the change in momentum of the ball in $MKS$ units?

$A$ ball of mass $0.5\, kg$ moving with a velocity of $2\, m/s$ strikes a wall normally and bounces back with the same speed. If the time of contact between the ball and the wall is $1\, ms$,the average force exerted by the wall on the ball is ......... $N$.