In view of the coronavirus pandemic, we are making LIVE CLASSES and VIDEO CLASSES completely FREE to prevent interruption in studies
Physics > Motion in a Straight Line > Average Velocity and Average Speed
Motion in a Straight Line

Average Velocity and Average Speed

Suppose an object is in motion, the position of that object changes with time. But how fast is the position changing with time and in what direction? To understand this, we define average velocity and average speed.

Suggested Videos

Play
Play
Play
Arrow
Arrow
ArrowArrow
Introduction to Motion
Distance, Displacement, Speed and Velocity
Acceleration-H
Slider

 

Average Velocity

Average velocity is the ratio of total displacement to total time. Its direction is the same as the direction of the moving object. Even if the object is slowing down, and the magnitude of the velocity is decreasing, its direction would be still the same as the direction in which the object is moving. The magnitude of average velocity is always less than or equal to the average speed because displacement is always smaller than or equal to distance.

It is a vector quantity and has units of m/s

Average velocity = \( \frac{Total Displacement}{Total Time} \)

The average velocity of the particle can be positive as well as negative and its positive and negative value depends on the sign of displacement. If the displacement of the particle is zero its average velocity is also zero.

Browse more Topics under Motion In A Straight Line

Calculating Average Velocity

The velocity of a particle is :

\( \vec{v} = \frac{d \vec{x}}{dt} \)

Learn more about Calculating Uniform Circular Motion.

Average Speed

The total distance travelled by the body in total time is the average speed.

Average speed = \( \frac{Total Distance}{Total Time} \)

It is a scalar quantity and its units are m/s.

 Calculating Average Speed

Average speed is found by the first finding the total distance covered by the object and dividing it by the total time taken in travelling the distance. Example: A body covers a circle of radius 100m on 100s, implies the total distance covered by him will be d = 2πr = 200π m. So, the average speed will be v= \( \frac{d}{t} \) = 2π m/s

If the motion of an object is along a straight line and in the same direction, the magnitude of displacement is equal to the total path length. In that case, the magnitude of the average velocity is equal to the average speed. In case the average speed is not equal to the magnitude of the average velocity, this is because the motion involves a change in direction and so path length is greater than the magnitude of displacement. So the average speed is greater than the magnitude of the velocity.

Learn how to calculate Instantaneous Speed and Velocity here

Solved Examples For You

Q. A particle moves for 20swith velocity 3m/s and then moves with velocity 4m/s for another 20s and finally moves with velocity 5m/s for next 20s what is the average velocity of the particle? (in m/s)

  1. 3
  2. 5
  3. 4
  4. zero

Answer: C

Q.2 An insect crawling straight down the length of a meter stick is at the 12cm mark at one instant, and 22 minutes later is at the 60cm mark. Which one of the following is the magnitude of the insect’s average velocity?

  1. 0.4cm/s
  2. 0.5cm/s
  3. 24cm/s
  4. 30cm/s

Answer: A. The total displacement of insect is S= 60-12 =48cm

Total time taken t= 2min =120s

Insect’s average velocity =  \( \frac{48}{120} \) = 0.4 cm/s

Share with friends

Customize your course in 30 seconds

Which class are you in?
5th
6th
7th
8th
9th
10th
11th
12th
Get ready for all-new Live Classes!
Now learn Live with India's best teachers. Join courses with the best schedule and enjoy fun and interactive classes.
tutor
tutor
Ashhar Firdausi
IIT Roorkee
Biology
tutor
tutor
Dr. Nazma Shaik
VTU
Chemistry
tutor
tutor
Gaurav Tiwari
APJAKTU
Physics
Get Started

Leave a Reply

avatar
  Subscribe  
Notify of

Stuck with a

Question Mark?

Have a doubt at 3 am? Our experts are available 24x7. Connect with a tutor instantly and get your concepts cleared in less than 3 steps.
toppr Code

chance to win a

study tour
to ISRO

Download the App

Watch lectures, practise questions and take tests on the go.

Get Question Papers of Last 10 Years

Which class are you in?
No thanks.