Dhiren M Doshi Solutions for Chapter: Force and Laws of Motion, Exercise 3: Check Your Progress

A cricket ball of mass $100 \mathrm{g}$ moving with a speed of $30 \mathrm{m}/\mathrm{s}$ is brought to a rest by a player in $0.03 \mathrm{s}$. Find the average force applied by the player.

Two bodies $A$ and $B$ of the same mass are moving with velocities $v$ and $3v$ respectively. Compare their momentum.

Two bodies $A$ and $B$ of the same mass are moving with velocities $v$ and $3v$ respectively. Compare the force needed to stop them in the same time.

A car weighing $1600 \mathrm{kg}$ is accelerated to $30 \mathrm{m}/\mathrm{s}$ from start in $20 \mathrm{s}$. Calculate the

a. initial momentum

b. final momentum

c. rate of change of momentum

d. acceleration of the car. 

e. magnitude of force applied.

A vehicle of mass $1000 \mathrm{kg}$ moving with a velocity of $20 \mathrm{m}/\mathrm{s}$ is brought to rest in $5$ seconds after covering a distance of $50 \mathrm{m}$.

a. Find the acceleration.

b. Calculate the unbalanced force acting on the vehicle.

c. The actual force applied by the brakes may be slightly less than that calculated in (b). Why? Give reason.

A body of mass $500 \mathrm{g}$ is resting on a frictionless table. Calculate the acceleration of the body when acted upon by a force of $0.01 \mathrm{N}$

A ball of mass $10 \mathrm{g}$ is initially moving with a velocity of $50 \mathrm{m}/\mathrm{s}$. On applying a constant force on the ball for $2\mathrm{s}$, it acquires a velocity of $70 \mathrm{m}/\mathrm{s}$. Calculate the 

a. initial momentum of the ball

b. final momentum of the ball

c. rate of change of momentum

d. acceleration of the ball

e. magnitude of the force applied.

A force acts for $10 \mathrm{s}$on a stationary body of mass $100 \mathrm{kg}$ after which it ceases to act. The body moves through a distance of $100 \mathrm{m}$ in the next $5 \mathrm{s}$. Calculate the

a. Velocity acquired by the body.

b. Acceleration produced by the force.

c. Magnitude of the force.