MOMENTUM

MOMENTUM

Momentum
The momentum possessed by a body is generally defined as the product of its mass and velocity.

Momentum is a vector and it also has magnitude as it is the product of the multiplication of the mass and velocity. Momentum also has distance which is found in the velocity of the body used in this context.

From Newton's second law it follows that, if a constant force acts on a particle for a given time, the product of force and the time interval (the impulse) is equal to the change in the momentum.

Conversely, the momentum of a particle is a measure of the time required for a constant force to bring it to rest.

The momentum of any collection of particles is equal to the vector sum of the individual momenta.

According to Newton's third law, the particles exert equal and opposite forces on one another, so any change in the momentum of one particle is exactly balanced by an equal and opposite change of the momentum of another particle.

Thus, in the absence of a net external force acting on a collection of particles, their total momentum never changes; this is the meaning of the law of conservation of momentum

Types of Momentum
Angular Momentum
Angular momentum is obtained by multiplying a body's mass by its angular velocity.

This means that a single body can have two types of angular momentum. For example, planetary bodies such as Earth have a first momentum that is calculated from the results of its motion in relation to the sun, and then an additional momentum calculated from the velocity of its spin on its own axis.

physics
The smaller the body is, the faster it will spin when it is being moved as a consequence of angular momentum.

This explains why figure skaters spin much faster when they are low to the ground and when their arms are wrapped around themselves, compared to when there are standing tall with arms wide-open.

Linear Momentum
Linear momentum, also known as force, is the quantity of mass associated with a body that moves along a straight path. An outside object, with its own force, can change the trajectory of an object with a linear momentum.

For example, if you are running forward and a dog runs into you by accident, your trajectory will be changed, and you may fall; however, you should not be hurt too badly because the momentum of the dog was similar to yours.

However, if you get hit by a truck, which has a higher linear momentum because of its high weight, you will be lucky to survive. That is because the truck's force is higher than yours.

The study of linear momentum also used to understand and predict how things change trajectory when they collide with another object, such as billiard balls do when hit by the cue ball.

In classical mechanics, linear momentum or translational momentum is the product of the mass and velocity of an object.

For example, a heavy truck moving fast has a large momentum—it takes a large and prolonged force to get the truck up to this speed, and it takes a large and prolonged force to bring it to a stop afterwards.

If the truck were lighter or moving more slowly, then it would have less momentum.

Linear momentum is also a conserved quantity, meaning that if a closed system is not affected by external forces, its total linear momentum cannot change.

In classical mechanics, conservation of linear momentum is implied by Newton's laws; but it also holds in special relativity (with a modified formula) and, with appropriate definitions, a (generalized) linear momentum conservation law holds in electrodynamics, quantum mechanics, quantum field theory, and general relativity.

Now that we have gathered lots of useful information about momentum, we will go further and tackle real momentum problems in physics with series of examples.

Example 1
Calculate the change in momentum cause by 50-kg car moving at 9 m/s.

Solution
Since M = m x v where m = mass and v is velocity

M = 50 x 9 = 450 kgm/s

Example 2
A lorry has a momentum of 200. What would be the car's new momentum if its velocity is tripled?

Solution
M = M x 3 = 200 X 3 = 600

You can now try your hands on the assignment listed below. Please make sure you attempt all the assignments before moving to the next topic.

Assignments
1. A ball having 5kg mass and 8m/s velocity moves to the west. Calculate the momentum of the ball.

2. A car which has 15m/s velocity and 1500kg mass moves towards north will have a momentum value of?