PHYSICS

MOTION

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 )

CONCEPT :-

Stationary body Moving body

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

MOTION

Stationary object

Moving object

Reference Point

Scalar :

• Gives only magnitude

Vector :

• Give both magnitude and direction

Vector and Scalar

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

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 and Non Uniform motion

Uniform Non Uniform

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

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.

Average and Uniform Speed

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.

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

Uniform Velocity

Average velocity :-

V = u + v t

Average Velocity

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