$A$ $8000 \,kg$ engine pulls a train of $5$ wagons,each of $2000 \,kg$,along a horizontal track. If the engine exerts a force of $40000 \,N$ and the track offers a friction force of $5000 \,N$,then calculate the acceleration (in $m/s^2$) of the train.

Name the physical quantity which corresponds to the rate of change of momentum.

In the following table,the mass and speed of two bodies are given. Which body has more momentum? Justify your answer.

Body	Mass $(kg)$	Speed $(m s^{-1})$
$A$	$1$	$10$
$B$	$2$	$9$

Prove that $1 \text{ N} = 10^{5} \text{ dynes}$.

$A$ bullet of mass $10\, g$ travelling horizontally with a velocity of $150\, m/s$ strikes a stationary wooden block and comes to rest in $0.03\, s$. Calculate the distance of penetration of the bullet into the block. Also,calculate the magnitude of the force exerted by the wooden block on the bullet.

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