An athlete runs for some distance before taking a long jump. Why?

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

An object of mass $m \, kg$ with speed $v \, m/s$ strikes a wall at an angle $\theta$ with the normal and rebounds at the same speed and same angle. The magnitude of the change in momentum of the object will be

The position-time graph for a particle of mass $100 \ g$ is shown in the figure. The impulse acting on the particle at $t = 5 \ s$ is ............ $N-s$.

$A$ $140\,g$ ball,in horizontal flight with a speed of $39.0\,m/s$,is struck by a bat. After leaving the bat,the ball travels in the opposite direction with a speed of $39.0\,m/s$. If the impact time $\Delta t$ for the ball-bat collision is $1.20\,ms$,calculate the average force in $N$ acting on the ball.

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