If a boy is running, then what is the reason for him not stopping suddenly. Or a boy is running then he cannot stop suddenly. Why?

A cricket ball of $100 \mathrm{g}$ moving with a velocity of $30 \mathrm{m}/\mathrm{s}$ is brought to rest by a player in $0.05 \mathrm{s}$. Find the change in momentum of ball in terms of  $\mathrm{kg} \mathrm{m} {\mathrm{s}}^{-1}$.

A cricket ball of $100 \mathrm{g}$ moving with a speed of  $30 \mathrm{m}/\mathrm{s}$ is brought to rest by a player in $0.05 \mathrm{s}$. Find the average force applied by the player in newton.

Define the following term: $1$ newton

Define the following term: $1$ dyne

Define the following term: $1$ g f.

Distinguish between the following statements:

(a) Force is proportional to acceleration.

(b) Force is equal to acceleration.