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Difference Between Momentum and Impulse

September 11, 2022
written by Adeel Abbas

The difference between momentum and impulse is that momentum is the force that keeps something moving while the impulse is the force that causes something to move. In physics, momentum is defined as the product of mass and velocity, and impulse is defined as the product of force and time.

Momentum and impulse are two terms that are often confused. In physics, momentum describes the rate at which something moves. Impulse is the amount of force applied over time.

When we talk about momentum, we are talking about how fast a body is moving. We use momentum to describe the speed of objects (e.g., cars). Impulse is the amount or force of a push or pull. If I push you, then my impulse is equal to the force that I am applying to you. If I throw a ball at you, then my impulse would be the same as the mass of the ball multiplied by its velocity.

What is Momentum?

Momentum is the product of the mass of an object and the velocity of the object. According to the second law of motion, the rate of change of a body’s momentum is the same as the net force acting on it.

If a closed system is not affected by external forces, its total linear momentum does not change, because it is a conserved quantity. In special relativity, a modified formula is used, as well as in a modified form, in quantum mechanics, quantum field theory, and general relativity. It is an expression of one of the fundamental symmetries of space and time. 

Momentum is denoted by p.

p=mv

where m is mass and v is the velocity of the object. The SI unit of momentum is kg m/s. It is a vector quantity.

What is impulse?

The term impulse quantifies the effect of a force acting over time. 

I=F.∆t

Where I is impulse F is force and ∆t is the very short interval time in which force act on the body. The impulse is the same as the force in that it is a vector quantity.

The effect of impulse applied to an object is the same as the effect of impulse applied to a different object in the same direction. The SI unit of impulse is the newton second (Ns), and the equivalent unit of momentum is the kilogram meter per second.

Difference Between Momentum and Impulse

There is some difference between momentum and impulse.

MomentumImpulse
Momentum is the product of mass and velocity.impulse is a product of force and a very short interval of time.
Momentum is conserved in an isolated system.Impulse is not a conservative force.
The rate of change of momentum is equal to the applied force.Impulse is equal to change in momentum.
The exact value can be determined by the product of mass and velocityThe exact value of impulsive force can not be determined because it does not remains constant.

Frequently Asked Questions-FAQs

What is impulsive force?

A large force that acts on a body for a very short interval of time is called impulsive force.

What is the SI unit of impulse?

Impulse is a vector quantity and its SI unit is Newton second.

What is the SI unit of momentum?

The SI unit of momentum is Newton Second or kilogram meter per second.

What is the relationship between momentum and impulse?

The time and force that an object experience is called the impulse. The mass-velocity change of an object is what’s referred to as the momentum change.

How is impulse used in real life?

The concept of impulse is being used to reduce the force of impact. The force on a tennis ball can be increased by having great racquet head speed. This increases the force of impact by decreasing the impact time between the ball and the racquet.