MOTION

PHYSICS

CONCEPT :-

Some objects in our surrounding are moving with respect to the stationary ones. Based on that object or body in our surroundings, our environment can be classified as :-

• Stationary Objects ( in rest )

• Moving Objects ( in motion )

Stationary body Moving body

MOTION

A body is said to be in motion when it’s position changes continuously with respect to reference point (stationary object).

• E.g.:- hand of the clock are in motion.

Reference point :-

• When a car moves in front of a forest

• With respect to the trees car is moving.

• Trees – reference point

Stationary object

Moving object

Reference Point

VECTOR AND SCALAR

Scalar : • Gives only magnitude

Vector : • Give both magnitude and direction

Displacement

Distance

e.g.

Scalar

Vector

Distance

•The length of actual path travelled by an object is known as Distance covered by the object.• It is a scalar quantity.

Displacement

•The shortest distance between the final and the initial point is called displacement.•Displacement is of scalar quantity

UNIFORM AND NON UNIFORM MOTION

A body travels in uniform motion when it travels equal distance in equal interval of time.

A body travels in Non uniform motion when it travels unequal distance in equal interval of time.

Uniform Non Uniform

SPEED

Speed:- distance travelled by a body per unit time ……….

speed = distance/time

Speed is scalar

Speedometer and Odometer are used to measure speed of an object

AVERAGE AND UNIFORM SPEED

Average speed :- The average speed of a body is the total distance travelled by the total time taken.

Average Speed = Total distance traveled / Total time taken

Uniform speed :- When the rate of change of position per unit time remains same the it is called uniform speed.

VELOCITY

Velocity :- distance travelled by a body per unit time in a given direction……

VELOCITY = displacement / time

Velocity is vector.

Direction of a body is as displacement at the body.

UNIFORM VELOCITY

Uniform velocity :- When the rate of change of position per unit time remains same the it is called uniform velocity.

Velocity of a body can be changed in the following 2 ways.By changing the speed of the bodyBy keeping the speed constant but by changing the direction

AVERAGE VELOCITY

Average velocity :-

V = u + v t

Acceleration

•The rate of change of velocity of an moving object is known as its Acceleration.• It is a vector quantity.•Acceleration =

Velocity/Time• It’s unit is m/sec2.

RETARDATION

• The rate of decreasing of velocity of a moving object is known as retardation.• It is also a vector quantity.

- PRATEEK SAXENA 9TH B14