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You are here: Home / Class 9 / Motion / velocity

velocity

Last Updated on May 4, 2020 By Mrs Shilpi Nagpal 1 Comment

Question 1 What name is given to speed in specified motion?

Question 2 Define Velocity?

Question 3 What is the S.I. unit of velocity?

Question 4 What is the difference between velocity and speed?

Question 5 When a body said to have uniform motion?

Question 6 How the velocity of a body can be changed?

Question 7 When a body said to have non-uniform motion?

Velocity
Velocity of a body is the distance travelled by it per unit time in a given direction.

formula of velocity

Distance travelled in a given direction is called as displacement.
S.I. unit of velocity is m/s or km/hr.
Velocity is a vector quantity.

For Example :25km/hr towards north.

The direction of velocity is same as the direction of displacement of the body.

Uniform velocity
A body has a uniform velocity if it travels in a specified direction in a straight line and moves over equal distances in equal interval of time,no matter how small these intervals may be.
Velocity of a body can be changed in 2 ways:
1) By changing speed
2) By changing direction

Non-uniform velocity
When a body does not cover equal distances in equal interval of time,the velocity is said to be non-uniform.
For Ex:car moving on circular road with constant speed.
Speed and velocity are equal in magnitude if body moves in a single line.

For Example: A———————–B
100 m
50 sec
east

               100
Speed = ——–
                50
= 2 m/s

                  100
Velocity = ——–
                  50
= 2 m/s
If a body does not move in a single straight line,then speed and velocity of body are not equal.

For Example:

A—————->B       100 km,50 sec  east
B—————-> A      100 km,50 sec west

               200
Speed = ——–
               100
= 2 m/s

                   0
Velocity = ——–
                  100
= 0 m/s

The average speed of a moving body can never be zero but average velocity of a moving body can be zero.

Filed Under: Class 9, Motion Tagged With: displacement, non-uniform velocity, uniform velocity, velocity

About Mrs Shilpi Nagpal

Author of this website, Mrs Shilpi Nagpal is MSc (Hons, Chemistry) and BSc (Hons, Chemistry) from Delhi University, B.Ed (I. P. University) and has many years of experience in teaching. She has started this educational website with the mindset of spreading Free Education to everyone.

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  1. vishal says

    March 2, 2021 at 7:41 pm

    thanks for you notes !!!

    Reply

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