How To Find Average Velocity: Different Methodologies And Problems


Average velocity is one of the basic functions to be determined in motion. In this article, we will know how to find average velocity.

The primary method to find average velocity is by taking the sum total of change in position of an object divided by total time taken by that object to complete its motion. Since it is a vector physical quantity the direction of the object also has an important effect in calculating average velocity.

Further we will study more methods on how to find average velocity as it is the post’s main focus.

What is the formula for average velocity

The primary formula used to calculate Vavg includes both displacement with time.

The general formula used is given as follows,

It is used in solving basic problems related to average velocity.

V = Sf – Si / t2 – t1

V = Δs/ Δt

Where,

Δs = displacement

Δt = time taken

Now let us see how to find average velocity with the help of distance and time.

How do you find average velocity with distance and time

The distance and time are the basic terms without which it is not possible to find average velocity.

First and foremost, we have to calculate the total length of the path along which an object has travelled, next we have to check the duration of time taken to reach the destination. Later to find the average velocity of this motion we need to make use of the previously calculated distance and time with the help of formula.

Now lets study further to know more approaches of finding average velocity.

How to find average velocity over an interval

After seeing the importance of distance and time in calculating average velocity. Now let us how to calculate it over an interval.

  • If you are calculating the average velocity on a graph then you to consider any two time and distance intervals and then find out the values of distance and time and substitute it in the average velocity formula.

                                                                     V = Sf – Si / t2 – t1

  • In other method, If you are directly going to use the formula then you must know the initial and end points so that it will be easy for you to calculate Vavg, you can even consider some portion of the interval to find Vavg It happens by taking total distance divided by total time.

                                    V = total distance/total time     or

V = (Vf + Vi) / 2

Now lets see the method to calculate Vavg between two points.

Average velocity between two points

Average velocity between two points can be found using the simple formula.

In general, we know that Vavg of a body is equal to arithmetic average of initial and end points that is given below

Vavg = [ Initial velocity (i) + Final velocity (v)] / 2

It is time to know how to find Vavg on a graph.

How to find average velocity on a graph

We can find average velocity with the help of displacement-time graph.

  • Here displacement will be on axis y and time on x axis.
  • Plot the points according to the axis and join them to create an area in the graph.
  • Then find out the total area in the graph by taking two intervals of time and distance.
  • Measure it along the line of graph and can be calculated using the formula

                                                   Vavg =(Vi+Vf)/2.

The variables taken on the graph has a prominent nature, all the factors such change of position (between initial and end points), nature of graph i.e., whether it is linear or not matters.

In this approach, we can calculate average velocity from the graph.

How to find average velocity on a linear graph

The linear graph is sometimes known as straight line graph.

If we want to know the average velocity on a linear graph, then we have to take both initial and final velocities and divide it by the number 2. It is similar to the average that we use in mathematics to solve certain problems.

Now lets know the condition to calculate average velocity in non-linear graph.

How to find average velocity on a non-linear graph

The non-linear graph can also be considered as the curved graph.

In non-linear graph what we can do to calculate the Vavg is we can consider the area under the graph that consists of displacement (integrate it) and then divide it by the time.

In this way we can calculate the Vavg in non-linear graph.

Average Velocity Example Problem

The given below is one of the basic problem that can be solved by using the approaches to calculate average velocity.

Example 1

Consider a person is travelling in his car to some destination, but during the starting 15s, the car position changes from x1 = 80 m to x2= 100 m. Now what is the average velocity of car?

Solution: Given the initial position is x1= 80m

                 Similarly, the final position is x2 = 100m

The change in the displacement of the car is calculated as follows:

Δx = x2 – x1 = 100 m – 80 m = 20 m

Δt = 15 s

From the formula we have,

v = Δx / Δt

v = 20/15

v= 1.33 m/s

Therefore, the average velocity of the car is found to be 1.33 m/s.

From the above problem we got to know one more approach of finding average velocity

Frequently Asked Questions | FAQs

What is Average Velocity?

Average velocity is a prominent phenomenon seen in physics.

It is a vector quantity and is defined as the ∆x divided by ∆t. Where ∆x signifies the displacement and ∆t tell about the total time taken by a body to complete the movement.  It may be sometimes positive or negative everything is based on the direction of displacement. It is denoted using the SI unit m/s.

How does average velocity differ from other velocities?

There are mainly two types of velocities which we usually come across in physics.

The two main type of velocities are average and instantaneous velocities. As their name suggests, average signifies the sum total of velocities of each interval calculated in total time. In contrast, instantaneous velocity will be the finding of velocity at a particular period of motion.

How is average velocity different from instantaneous velocity in a particular time interval?

If we take a particular time interval then there is difference in measuring average and instantaneous velocity.

The primary difference is for a particular period of interval the instantaneous velocity is measured with displacement and time at a certain point (s,t) and the average velocity is considered to be the overall change in position with time in a certain time interval.

Does average velocity remains same in motion?

Velocity do not remain same in a particular motion it keeps on varying.

We have studied that the velocity is a variable depending on many factors. It does not remain constant but keeps changing its value with the help of displacement and time of that object. From this we can tell that average velocity does not remain same in a motion.

What are the main two different ways to calculate average velocity?

There are many applications through which we can measure average velocity easily.

The first method is to find the average velocity by taking the first and end points of a motion, subtracting it and later dividing the whole term by 2.

The second method is by using the formula known as average velocity equation.

Average Velocity Equation = V = (Vf + Vi)/2

  • V = average velocity.
  • Vf = final velocity.
  • Vi = initial velocity

It is the prime equation to measure average velocity.

How do you find displacement with average velocity?

There are many ways to find displacement in kinematics.

One of them is to find displacement with the help of average velocity formula that consists of change in position/displacement. By interchanging the terms of formula we can make use of it to calculate the displacement.

Why are average speed and average velocity different?

Both the terms mean entirely different from one another, when we study about them in physics.

Here we know that speed is a scalar and velocity is vector, then the major difference comes from the physical quantities that measures the significance of how they can be measured.

Difference Between Average Speed and Average Velocity

The primary difference between these two quantities are given below,

  • Average velocity tells about only position of the body in motion, here we must notice that magnitude will be different for each position and to find the velocity at any time interval on the length of the course is done with the help of average velocity.
  • Average speed tell about the maintainance of speed on the whole path of the motion. It is the sum total of speed calculated by taking into consideration total path length and time and since it is a scalar we cannot the direction of the path.

Raghavi Acharya

I am Raghavi Acharya, I have completed my post-graduation in physics with a specialization in the field of condensed matter physics. Having a very good understanding in Latex, gnu-plot and octave. I have always considered Physics to be a captivating area of study and I enjoy exploring the various fields of this subject. In my free time, I engage myself in digital art. My articles are aimed towards delivering the concepts of physics in a very simplified manner to the readers. Let’s connect through - LinkedIn: https://www.linkedin.com/in/raghavi-c-s-260a801b1 EMAIL ID: raghavics6@gmail.com

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