Law of Conservation of Linear Momentum: Overview, Questions, Preparation

Linear momentum is a vector quantity and can be defined as the relationship between the velocity and the mass of the particle. Conservation of linear momentum can be explained as the principle in which the total amount of momentum remains constant and never changes.

The momentum remains constant when the external force is zero. It must be noted that the momentum of the Individual body can be increased or decreased, but the momentum of the system remains constant.

The conservation of Linear Momentum states the initial momentum and the final momentum. It is said that if any objects collide, the before and aftermath of the total momentum of the collisions will be the same if the force is zero. The values will change with the change in the force of the objects; when the external force is zero, initial momentum = final momentum.

It is written as:

P_i = P_f

Newton’s second law of motion describes the conservation of linear momentum. It says that the net external force applied to the linear momentum is equal to the rate of change of linear momentum of a body.

It can be expressed as:

dP / dt

= (mv) / dt

= m dv/dt

= ma

= F_net

The rate of change of linear momentum will be zero if the net external force is zero. It simply means the change in momentum is zero.

Let us consider the two bodies with the mass M and m moving in the opposite directions to each other, and the velocity is v. Let us assume that they collide and are moving together even after the collision, let us find the velocity of the system.

The equation is written as:

(Mv – mv) = (M + m) V_Final

• It is used for launching rockets because the exhaust gases are pushed downwards with the burn of the rocket fuel.
• Similarly, with the motorboats, the water is pushed backwards and then forward to conserve the momentum.

Conservation of linear momentum for Class 11

The chapter 'Conservation of Linear Momentum' holds a weightage of 8 marks. It includes 2 questions in total, consisting of one short type question of 3 marks and one long question of 5 marks.

Example 1) Write the three laws of conservation.

Answer – The three laws of conservation are as follows:

• Conservation of linear momentum
• Conservation of angular momentum
• Conservation of electric charge

Example 2) Write the equation of conservation of linear momentum.

Answer – It can be expressed as:

dP / dt

= (mv) / dt

= m dv/dt

= ma

= F_net 

Example 3) Write the consequence of the law of conservation of charge.

Answer – Charge, momentum, mass, or energy are the consequence of the law of conservation of charge.

Q: What do you mean by Conservation of Linear Momentum?

Q: What is the formula of Conservation of Linear Momentum?

Q: Who discovered the law of conservation of linear momentum?

Q: What are the applications of conservation of linear momentum?

Q: Write a principle of environmental conservation.