Linear Momentum & its Conservation (CIE A Level Physics)

A tennis ball of mass 60 g is struck by a tennis racket. The velocity of the ball changes as shown

What is the magnitude of the change in momentum of the ball?

Two spheres approach each other along the same straight line. Their speeds are  and before collision, and and after collision, in the directions shown below

Which equation is correct if the collision is perfectly elastic?

A lorry of mass 18 tones is travelling at 25.0

A car of mass 800 kg is travelling at 40.0 towards the lorry.

What is the magnitude of the total momentum?

The diagram shows the masses and velocities of two trolleys about to collide

After the impact they move off together

What is the total kinetic energy of the trolleys after the collision?

The diagram shows a cannon ball fired from a cannon

The mass of the cannon is 1600 kg and the mass of the cannon ball is 20 kg

The recoil velocity of the cannon is 5 horizontally

 What is the horizontal velocity of the cannon ball?

A ball of mass 2 kg travelling at ½   strikes a ball of mass 3 kg travelling at ⅓ .  Both balls are moving along the same straight line as shown

After collision, both balls move at the same velocity v

What is the magnitude of the velocity v?

A molecule of mass m travelling at speed v hits a wall in a direction perpendicular to the wall. The collision is elastic.

What are the changes in the momentum and in the kinetic energy of the molecule caused by the collision?

	Change in momentum	Change in kinetic energy
A B C D	0 mv mv2 2mv	0 mv2 0 0

A moving object strikes a stationary object. The collision is inelastic. The objects move off together.

Which row shows the possible values of total momentum and total kinetic energy for the system before and after the collision?

	Total momentum before collision / kg m s–1	Total momentum after collision / kg m s–1	Total kinetic energy before collision / J	Total kinetic energy after collision / J
A B C D	6 6 6 6	6 6 2 6	90 30 90 90	30 90 30 90

A resultant force of 5 N acts on a body for a time of 4.0 s

Which graph could show the variation with time t of the momentum p of the body?

Two train carriages each of mass 7500 kg roll toward one another on a level track. One is travelling at 3.00 m s⁻¹ and the other at 1.50 m s⁻¹ as shown.

They collide and join together.

What is the kinetic energy lost during the collision?

A fully fuelled rocket travels at 13 m s⁻¹. The rocket engines are fired, and all the fuel is used. The rocket now travels at 16.9 m s⁻¹ in the same direction. The mass of the rocket without fuel is 1000 kg. 

What is the mass of the fuel?

Trolleys A and B have a mass of 5000 kg each. Trolley A travels towards Trolley B. Trolley B travels at 2 ms⁻¹ in the opposite direction. The trolleys collide and join together with a combined kinetic energy of 1250 J. What was the velocity of Trolley A before the collision?

Two billiard balls of identical mass collide. The first ball hits the second with a speed of 30 m s⁻¹ at an angle of 45^o to the direction that the second ball moves in after the collision, v.  At what speed does the second ball move after the collision?

A wooden block is freely supported on brackets at a height of 4.0 m above the ground, as shown

A bullet of mass 10.0 g is shot vertically upwards into the wooden block of mass 150 g. It embeds itself in the block. The impact causes the block to rise above its supporting brackets.

 The bullet hits the block with a velocity of 200 m s^–1. How far above the ground will the block be at the maximum height of its path?

Two railway trucks of masses m and 5 m move towards each other in opposite directions with speeds 3 u and u respectively. These trucks collide and stick together.

 What is the speed of the trucks after the collision?

Sand falls vertically on a conveyor belt at a rate of m kg s^–1

In order to keep the belt moving at constant speed v, the horizontal force that must be exerted is equal to 

A stationary body explodes into two components of masses m and 3 m.

The components gain kinetic energies X and Y respectively.

What is the value of the ratio  ?

A lead pellet of mass 20.0 g is shot horizontally into a stationary wooden block of mass 80.0 g. The pellet hits the block with an impact velocity of 250 m s^–1. It embeds itself in the block and it does not emerge.

After the impact, the block and the pellet continue to move for 8.4 s, how far do they travel in this time?

A stationary nucleus has nucleon number A.

The nucleus decays by emitting a proton with speed v to form a new nucleus with speed u. The new nucleus and the proton move away from one another in opposite directions.

Which equation gives  in terms of A and u?

A particle X has speed v and collides with a stationary identical particle Y. The collision is perfectly elastic.

 What are the speed and direction of motion of each of the two particles after the collision?

 

	X	Y
A	stationary	v to the right
B	to the right	to the right
C	to the left	to the right
D	v to the left	stationary

 

The diagram shows two spherical masses approaching each other head-on at an equal speed u. One is of mass m and the other of mass 2 m.

Which diagram, showing the situation after the collision, is not consistent with the principle of conservation of momentum?

An ice-hockey puck slides along a horizontal, frictionless ice-rink surface. It collides inelastically with a wall at right angles to its path, and then rebounds along its original path.

Which graph shows the variation with time t of the momentum p of the puck?

A body, initially at rest, explodes into two masses M₁ and M₂ that move apart with speeds v₁ and v₂ respectively.

 What is the ratio   ?