The force $F$ acting on a particle of mass $m$ is indicated by the force-time graph shown below. The change in momentum of the particle over the time interval from $0 \, s$ to $8 \, s$ is .......... $N-s$.

$A$ body of mass $5 \,kg$ is moving with a velocity of $\vec{v}=(2 \hat{i}+6 \hat{j}) \,m/s$ at $t=0 \,s$. After time $t=2 \,s$,the velocity of the body is $(10 \hat{i}+6 \hat{j}) \,m/s$. The change in momentum of the body is ......... $kg \cdot m/s$.

$A$ machine gun fires a bullet of mass $35 \ g$ with a speed of $600 \ m/s$. The person holding the gun can exert a maximum force of $147 \ N$ on it. The number of bullets that can be fired from the gun per second is

$A$ golf ball of mass $50 \text{ g}$ placed on a tee is struck by a golf club. The speed of the golf ball as it leaves the tee is $100 \text{ m/s}$, and the time of contact with the ball is $0.02 \text{ s}$. If the force decreases to zero linearly with time, then the force at the beginning of the contact is (in $\text{ N}$)

Figures $I, II, III$ and $IV$ depict the variation of force with time. In which of these situations is the impulse the highest?

Which force acts on a body first: action or reaction?