# How to calculate  momentum

This lesson will show you how to calculate the momentum using the mass and velocity.

Does it make sense though why we need the mass and the velocity?

Look at the two vehicles below and tell me which vehicle will require more effort to stop?

A 2500 pounds car moving 50 miles per hour or a 20,000 pounds truck moving 50 miles per hour.

It will be harder to stop the truck, so we say that the truck has more momentum.

Momentum thus depends on the mass. Which vehicle will require more effort to stop?

A 2500 pounds car moving 5 miles per hour or a 2500 pounds car moving 90 miles per hour.

It will be harder to stop the 2500 pounds car moving 90 miles per hour, so we say that the car with the greater velocity has more momentum.

Momentum thus depends also on the velocity.

Definition of momentum:

The momentum of an object is the product of the mass and the velocity. ﻿

momentum = mass × velocity

momentum = mv

When direction is not important, we can use instead the following formula.

momentum = mass × speed = mv

Notice that we still use v as an abbreviation for the velocity or the speed when direction is important or not.

Resist the urge though to think that mass has more bearing on the momentum.

It is quite possible that a bicycle can have more momentum than a truck.

A bike weighing 40 pounds moving with a speed of 30 miles per hour will have more momentum than a truck moving 5 miles per hour.

An object at rest has no momentum because it has no speed even though the mass is still there.

It is easy to see. Since v = 0, momentum  = m times 0 = 0

The concept of momentum applies only to moving objects. It is basically inertia in motion.

However, once an object is in motion, both mass and speed are taken into account.

From what we have seen so far, you may have realized that a moving object can have a large momentum if either the mass or the speed is large or both.

Unit of momentum: The mass is expressed in kg and the velocity can be expressed in m/s

The momentum is thus expressed in kg.m/s

This lesson on how to calculate momentum is over.

## Recent lesson 1. ### Law of Reflection

Mar 16, 17 03:15 PM

Great lesson about the law of reflection. Crystal clear explanation