LESSON 5: IMPULSE AND MOMENTUM
Introduction
The law of conservation of energy, which discussed in the previous lesson is one of several great
conservation laws in physics. Among the other quantities found to be conserved is linear momentum.
I this lesson, conservation of linear momentum and energy will be used to analyze collisions.
Collisions as between billiard or pool balls that illustrates vector law very effectively. The total vector
momentum before collision equals the total vector momentum after collisions.
Learning Outcomes
After successful completion of this lesson, you should be able to:
Relate Newton’s second Law of Motion to impulse and momentum.
Calculate the impulse of a force and relate it to the change in momentum.
Distinguish between internal and external forces among interacting bodies.
Recognize when momentum is conserved.
Apply the impulse — momentum relation and the conservation of momentum to a variety of
problems involving collisions (elastic and inelastic) and other kinds of interaction between bodies.
Discussion
5.1 Linear Momentum
Momentum is a property related to an object’s motion and mass. The faster the object moves and
the larger its mass, the greater is its momentum. It is the tendency of an object to continue moving at
constant velocity and thereby encountering difficulty in bringing the object to rest. The linear
momentum p is defined quantitatively as the product of its mass m and velocity v:
Momentum = p = mv
The Unit Of Momentum is
Since velocity is a vector quantity having magnitude and direction, momentum is also a vector
quantity with magnitude and direction. The direction of an object’s momentum equals the direction of
its velocity.
5.2 Impulse
