- Submitted By: SyedKhan
- Date Submitted: 08/30/2011 12:47 AM
- Category: Science
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Lecture-5

Momentum: Momentum is the product of the mass and the velocity of an object. It is denoted by P. The SI unit of momentum is kgms-1. If the mass of an object is m and velocity is v then its momentum is,

P = mv

Inertia: Inertia is the resistance of an object to a change in its state of motion. In other word for which a body in motion tends to remain in motion, a body at rest tends to remain at rest is called inertia.

Newton's laws of motion

Newton's laws of motion are three physical laws that form the basis for classical mechanics, directly relating the forces acting on a body to the motion of the body. They were first compiled by Sir Isaac Newton in his work Philosophiae Naturalis Principia Mathematica, first published on July 5, 1687

First law: An object at rest tends to stay at rest and an object in motion tends to stay in motion with the same speed and in the same direction unless acted upon by an unbalanced net force.

Second law: The rate of change of momentum of a body is proportional to the applied force and takes place in the direction in which the force acts.

Third law: For every action there is an equal and opposite reaction.

Relation between force and mass: From Newton’s law we can make a relation between force and mass and that is, F = ma. Where F is force in Newton unit, m is mass in kg unit and ‘a’ is acceleration.

Law of conservation of momentum: The total momentum of a group of objects remains the same unless outside forces act on the objects. The simple example of this law is two body collisions. Since momentum is conserved, sum of the momentum before the collision must be equal the sum of the momentum after the collision, so:

[pic]

Where,

‘u’ signifies velocity before collision

‘v’ signifies velocity after collision &

‘m’ signifies mass of the object

1. Imagine a place in the cosmos far from all gravitational and frictional influences. Suppose that you visit that place (just suppose) and throw a rock....