Angular Velocity:

Angular Velocity: The angle subtended by the line joining the object from the origin of circle in unit time interval is called angular velocity.

It is generally denoted by Ѡ = 2,, / T  = 2n.

In one revolution, the object travels 2r distance.

Linear speed = Ѡr = angular speed x radius

Newton’s laws of motion: Newton, the father of physics established the laws of motion in his book, “principia “in 1687.

New ton’s first law of motion: Everybody maintains its initial state of rest or motion with uniform speed on a straight line unless and external force acts on it.

First law is also called law of Galileo or law of inertia.

Inertia: inertia is the property of a body by virtue of which the body opposes change in its initial state of rest or motion with uniform speed on a straight line.

Inertia is of two types (i) Inertia of rest (ii) Inertia of motion

Some examples of inertia:

(i)                  When a car or train starts suddenly, the passengers bends backward.

(ii)                When a running horse stops suddenly, the rider bends forward.

(iii)               When a coat / blanks is beaten by a stick, the dust particles are removed.

First law gives the definition of force.

Force: Force is that external cause which when acts on a body changes or tries to change the initial state of the body.

Momentum: Momentum is the property of a moving body and is defined as the product of mass and velocity of the body i.e.

Momentum= mass x velocity.

It is a vector quantity. Its SI unit is kgm / s.