Law of Conservation of Momentum

A certain force exerted for $0.5 \mathrm{s}$ raises the speed of an object from $2.4 \mathrm{m}/\mathrm{s}$ to $4.9 \mathrm{m}/\mathrm{s}$. Later the same force is applied for $2.5 \mathrm{s}$. How much does the speed of object change in $2.5 \mathrm{s}$?

Discuss the conservation of momentum in each of the following cases:

Launching of rocket from the ground.

A $40 \mathrm{kg}$ shell is moving with a velocity of $72 \mathrm{km}/\mathrm{h}$. It explodes into two pieces, of which one piece of mass $15 \mathrm{kg}$ stops immediately. Calculate the velocity of the other piece.  

State the law of conservation of momentum. Explain how this law is valid for

a. recoiling of a gun

b. motion of a rocket

Why do we get hurt more by falling on a concrete structure than on a sand track?

How does a cricketer avoid getting hurt, while catching a ball?

Give an example in which momentum changes even though speed and mass remain the same.

An object of mass $2 \mathrm{kg}$ travelling along a straight line with a velocity of $5 \mathrm{m}/\mathrm{s}$ collides with and sticks to a stationary wooden block of mass $8 \mathrm{kg}$. Then they both move off together in the same straight line. Calculate the total momentum just before the impact and just after the impact. Also calculate the velocity of the combined object.

A hunter fires a bullet of mass $10 \mathrm{g}$ with a velocity of $400 \mathrm{m}/\mathrm{s}$ from a gun of mass $5 \mathrm{kg}$. What will be the recoil velocity of the gun?

A bullet of mass $10 \mathrm{g}$ moving with a velocity of $400 \mathrm{m}/\mathrm{s}$ gets embedded in a freely suspended wooden block of mass $900 \mathrm{g}$. What is the velocity acquired by the block?

Calculate the recoil velocity of a $4 \mathrm{kg}$ gun which shoots a $0.05 \mathrm{kg}$ bullet with a speed of $280 \mathrm{m}/\mathrm{s}$.

State the law of conservation of momentum.