An athlete runs some distance before taking a long jump,because

What would happen if a fielder stops a fast-moving ball suddenly? Justify your answer.

$(a)$ Define momentum and mention its $SI$ unit.
$(b)$ From the velocity-time graph shown in the figure for a body of mass $5\, kg$,find the force on the body from:
$(i)$ $O$ to $A$ and $(ii)$ $B$ to $C$.
$(c)$ Which would require a greater force: accelerating a $2\, kg$ mass at $5\, m s^{-2}$ or a $4\, kg$ mass at $2\, m s^{-2}$?

State whether the following statement is true or false:
$1 \ N$ is the force that produces an acceleration of $1 \ m \ s^{-2}$ in a body of mass $1 \ g$.

$A$ man is at rest in the middle of a pond on perfectly smooth ice. He can get himself to the shore by making use of Newton's:

$(a)$ Define momentum. Write its $SI$ unit.
$(b)$ $A$ bullet of mass $0.02 \ kg$ is fired from a gun weighing $7.5 \ kg$. If the initial velocity of the bullet is $200 \ m \ s^{-1}$,calculate the speed with which the gun recoils.