Newton’s first law | Mechanics

Newton’s first law 

• According to this law if a body is stationary then it will remain stationary and if it is moving then it will move with the same velocity and in same direction until and unless an external force is applied on it.
• This law gives the qualitative definition of force. The force is that external cause which tend to change or actually change the state of motion of the body.
• This law also provide us the concept of inertia and the concept of inertia was given by Galileo and hence it is also known as Galileo’s law of inertia.

Inertia

• Inertia is that inherent property of a body due to which a body opposes the change in its state.
• Inertia ∝ Mass
• Thus greater is the mass of the body, larger is the inertia.

Types of inertia

Inertia of rest

• It is the inability of the body to change its state of rest by itself.

Example

• A person standing in a bus falls backward, when the bus suddenly start moving.
• The dust particles inside a woolen blanket fall off when it is beaten by a stick.

Inertia of motion

• It is the inability of the body to change its state of motion by itself.

Example

• A man getting down of a moving bus falls forward, when the bus suddenly stops.
• A ball thrown upwards in a running train continues to move along with the train.

Inertia of direction

• It is the inability of a body to change its direction itself.

Example

• When a car suddenly takes a turn, the passengers are thrown in the outward direction.
• A body released from a balloon rising up, continues to move in the direction of balloon.

To know more about Newton's first law of motion please click on https://youtu.be/hs5hATc3GII