Type of Inertia

The  inertia  is  of  three  types

(i)Inertia  of  rest

(ii)    Inertia  of  motion

(iii)   Inertia  of    direction.

(i)     Inertia  of  rest

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

Examples

(i)  A  person  standing  in  a  bus  falls  backward  when  the  bus

suddenly starts moving. This is because, the person who is initially at

rest  continues  to  be  at  rest  even  after  the  bus  has  started  moving.

(ii) A book lying on the table will remain at rest, until it is moved

by  some  external  agencies.

(iii) When a carpet is beaten by a stick, the dust particles fall off

vertically downwards once they are released and do not move along the

carpet  and  fall  off.

(ii)  Inertia  of  motion

Inertia  of  motion  is  the  inability  of  the  body  to  change  its  state  of

motion  by  itself.

Examples

(a) When a passenger gets down from a moving bus, he falls down

in  the  direction  of  the  motion  of  the  bus.

(b) A passenger sitting in a moving car falls forward, when the car

stops  suddenly.

(c)  An  athlete  running  in  a  race  will  continue  to  run  even  after

reaching  the  finishing  point.

(iii)  Inertia  of  direction

It  is  the  inability  of  the  body  to  change  its  direction  of  motion  by

itself.

Examples

When a bus moving along a straight line takes a turn to the right,

the  passengers  are  thrown  towards  left.  This  is  due  to  inertia  which

makes the passengers travel along the same straight line, even though

the  bus  has  turned  towards  the  right.