Lesson 27 ā Activity 2: Conservation of Momentum
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Lesson 27 ā Activity 2: Conservation of Momentum
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In this activity, you will learn about momentum and the law of conservation of momentum. You will also learn how the laws of motion, designed by a scientist named Sir Isaac Newton, reflect the law of conservation of momentum.
Momentum is a measure of a moving body and how likely it is that it will remain in motion. Force is any push or pull on an object. The size of the force required to move an object depends on the mass of the object, how long you apply force, and how fast you want to make the object go.
Objects that are not moving will not move until they are pushed or pulled with enough force. Objects that are moving will keep moving until enough force is added in an opposite direction to stop them. Objects with a lot of momentum will take longer and more force to stop.
You may recall from other lessons the law of conservation of energy: energy cannot be created nor destroyed
You might also remember the law of conservation of matter: matter cannot be created nor destroyed
The law of conservation of momentum is very similar:
momentum cannot be created nor destroyed
This law makes sense when you think about it in terms of the laws of Sir Isaac Newton. Sir Isaac Newton was a scientist who made several interesting discoveries about some important concepts, including gravity. As part of his work, Newton made three theories to describe or explain the way things move.
You can read about the laws of motion and see how these laws reflect the law
of conservation of momentum by clicking below.
Newton's First Law of Motion:
An object at rest tends to stay at rest, and an object in motion tends to stay in motion, moving at the same speed and in the same direction unless it is affected by an outside force.
According to this law, then, momentum tends to stay the same, or be conserved.
Newton's Second Law of Motion:
The change of motion of a body is directly proportional or dependent to the outside force being applied on the object.
This law also reflects the law of conservation of momentum. For example, if a parked car is hit by a moving car, the parked car will move and the moving car will slow down (and sometimes stop) so that the overall momentum of the two vehicles is conserved.
Newton's Third Law of Motion:
For every action force, there is an equal and opposite reaction force.
This law also reflects the law of conservation of momentum. For example, if two cars have a head-on collision, the force each car exerts on the other will be the same, but it will be in the opposite direction. In other words, momentum is conserved.
Scientists measure momentum by multiplying the mass of an object times its velocity (how fast it is going):
Momentum = Mass x Velocity
When calculating momentum:
- mass is usually expressed in kilograms (kg)
- velocity is usually expressed in metres per second (m/s)
- momentum is usually expressed in kilogram metres per second (kgā¢m/s)
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