Motion Class 9 Notes Science Chapter 8
which remains Fixed at a place is called Stationary object.
E.g:-Trees, a house, a school, a factory
Object:- The object
which can move from one place to another is called moving object.
E.g:- a man moves when he walks along a
road, a bird moves when it flies in the
Note:- A common characterstics of all the
moving bodies is that they change their position with time.
Point:- A body is
said to be in motion (or moving) when its position changes contiously with
respect to a stationay object taken as reference point.
Note:-If a body moves fairly fast, then
its movement(or motion) can be observed easily. But if a body moves very
slowly, the it become difficult to observe its movement immediately.
E.g:- A wrist watch has
three hands:- a second hand, a minute hand and an hour hand, which moves round
and round on the dial of the watch. Now, the seconds’ hand of watch moves quite
fast, so we can observe the movement of the second hand of watch very easily.
But the minutes hand and an hour hand of a watch moves quite slowly, so their
movement cannot be observed easily.
Motion:- The body is said to be in motion
when its position changes continuously with respect to time.
Note:- Physical quantity:- The quantity
which can be measured or quantities of Physics
E.g. The quantity like distance,
displacement, etc. are known as physical quantity.
physical quantity having only magnitude( or size) is known as a scalar
E.g:- Distance, speed, mass, length, time
physical quantity having magnitude as well as direction is called vector
E.g:- Displacement, velocity,
acceleration, force, moventum, torque, Angular movementum
Travelled and Displacement
Distance(‘D’):- The distance travelled by a body is
the actual length of the path covered by a moving body irrespective of the
direction in which the body travels.
to another, the shortest(straight line) distance between the initial position
and final position of the body, along with direction, is known as its
Note:- If we a round trip and reach back at the starting point then, though we have travelled some distance, our final displacement will be zero. This is because the straight line distance between the initial and final position will be zero.