Average Speed and Average Velocity - Definition, Formula, Example, FAQs

Edited By Vishal kumar | Updated on Jul 02, 2025 04:24 PM IST

In studying physics, we have two concepts to deal with when it comes to motion: speed and velocity. Velocity is a term used to describe how fast an object is moving with respect to its direction. Whereas, speed only tells only about how fast an object is moving.

Let's undertsand the difference between speed and velocity with the help of an example: If someone tells you that he is driving at $60 \mathrm{Km} / \mathrm{hr}$ then he is talking about the speed. On the other hand, if someone tells you that he is driving at $60 \mathrm{Km} / \mathrm{hr}$ in the north direction then he is talking about the velocity.

This Story also Contains

What is Speed?
What is Velocity?
What is Average Speed?
What is Average Velocity?
Common Mistakes and Misconnects

Average Speed and Average Velocity - Definition, Formula, Example, FAQs

In this article, we will clarify the difference between speed and velocity show you how to determine both, and bring examples for better understanding.

What is Speed?

Speed is used to define how fast the object is moving with respect to time. It is a scalar quantity, which means it has no direction. Speed is calculated by dividing the total distance by the total time required to cover that distance.

$$
\text { Speed }=\frac{\text { Distance }}{\text { Time }}
$$

where,

Distance is the total path covered, and Time is the duration taken to cover that distance.

S.I Unit of speed is meters per second (m/s).

What is Velocity?

Velocity is a vector quantity, meaning it has both a magnitude and a direction. It indicates how quickly an object is moving or changing position. The velocity vector's direction is simple to determine. It moves in the same direction as the moving object. Even if the item is slowing down and the magnitude of velocity is decreasing, the object's direction will remain the same.

$$
\text { Velocity }=\frac{\text { Displacement }}{\text { Time }}
$$

where,

Displacement is the straight-line distance from the starting point to the end point, and time is the duration taken to complete this displacement.

S.I Unit of speed is velocity is meters per second $(\mathrm{m} / \mathrm{s})$.

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What is Average Speed?

Average speed is defined as the total distance travelled divided by the total time taken to cover that distance. It represents the overall rate of motion, without accounting for changes in speed during the journey.

The formula for average speed is:

$$
\text { Average Speed }=\frac{\text { Total Distance }}{\text { Total Time }}
$$
Let's understand the concept of average speed by a numerical problem.

Example:

Rahul rode his motorcycle from Pune to Nagpur for two hours at 60 kmph and three hours at 70 kmph. Calculate average speed

Solution:

To calculate Rahul's average speed for the entire trip, we need to find the total distance travelled and the total time taken.

- For the first part of the trip ( 2 hours at $60 \mathrm{~km} / \mathrm{h}$ ):

$
\text { Distance }_1=\text { Speed } \times \text { Time }=60 \mathrm{~km} / \mathrm{h} \times 2 \text { hours }=120 \mathrm{~km}
$

- For the second part of the trip ( 3 hours at $70 \mathrm{~km} / \mathrm{h}$ ):

$
\text { Distance }_2=\text { Speed } \times \text { Time }=70 \mathrm{~km} / \mathrm{h} \times 3 \text { hours }=210 \mathrm{~km}
$

$
\text { Total Distance }=\text { Distance }_1+\text { Distance }_2=120 \mathrm{~km}+210 \mathrm{~km}=330 \mathrm{~km}
$

$
\text { Total Time }=2 \text { hours }+3 \text { hours }=5 \text { hours }
$

$
\text { Average Speed }=\frac{\text { Total Distance }}{\text { Total Time }}=\frac{330 \mathrm{~km}}{5 \text { hours }}=66 \mathrm{~km} / \mathrm{h}
$
Answer- $
66 \text { km/h }
$

What is Average Velocity?

Average velocity is defined as the total displacement (change in position) divided by the total time taken. It is a vector quantity, meaning it has both magnitude and direction, and it indicates the overall direction and rate of motion.

The formula used to calculate average velocity is:

$
\text { Average Velocity }=\frac{\text { Total Displacement }}{\text { Total Time }}
$

The numerical examples below will help you understand the idea of average velocity.

Example:

On the x-axis, what is the average velocity of a person moving 7 meters in 4 seconds and 18 meters in 6 seconds?

Solution:
The person moves 7 meters in the first part and 18 meters in the second part. Assuming both displacements are in the same direction along the $x$-axis, the total displacement is:

$$
\text { Total Displacement }=7 \mathrm{~m}+18 \mathrm{~m}=25 \mathrm{~m}
$$

$$
\text { Total Time }=4 \mathrm{~s}+6 \mathrm{~s}=10 \mathrm{~s}
$$

$$
\text { Average Velocity }=\frac{\text { Total Displacement }}{\text { Total Time }}=\frac{25 \mathrm{~m}}{10 \mathrm{~s}}=2.5 \mathrm{~m} / \mathrm{s}
$$
The average velocity of the person is $2.5 \mathrm{~m} / \mathrm{s}$ along the x -axis.

Related Topics,

Common Mistakes and Misconnects

The average velocity does not have to be the same magnitude as the average speed. People may believe that average speed and average velocity are the same thing, but average speed is determined by distance, while average velocity is determined by displacement. If an object reverses direction throughout its travel, its average speed will be greater than the average velocity's magnitude.

Average velocity is a vector, and speed is a scalar. When the displacement is in the negative direction, the average velocity can be represented as a negative integer. The average speed has no meaning in terms of direction and can only be positive or negative.

Frequently Asked Questions (FAQs)

1. What's the relationship between average velocity and average speed?

Because displacement is always less than or equal to the distance travelled, the magnitude of average velocity is always less than or equal to the average speed. The formula V = D/t is used to calculate average velocity, where V equals average velocity, D equals total displacement, and t equals total time.

2. What is the average velocity formula?

The formula V = D/t is used to calculate average velocity, where V equals average velocity, D equals total displacement, and t equals total time.

3. What is the definition of beginning velocity?

Anything will accelerate as a result of forces acting on it. The object's velocity changes as a result of this acceleration. As a result, the initial velocity is the object's velocity before acceleration, which produces the change.

4. What is the International System of Units (SI) for velocity?

Velocity is a physical vector quantity that requires both magnitude and direction to define. Speed is a coherent derived unit whose quantity is measured in the SI (metric system) as meter per second (m/s or ms^-1).

5. What do you mean when you say "average speed"?

For example, we might say that a car travels at 25 miles per hour on average. Due east, its average velocity could be 25 miles per hour. The rate of change in distance with respect to time can be thought of as average speed.

6. What's the difference between average speed and average velocity?

Average speed is the total distance traveled divided by the total time taken, regardless of direction. Average velocity, however, is the displacement (change in position) divided by the time taken, considering both magnitude and direction. Speed is a scalar quantity, while velocity is a vector quantity.

7. Can average speed ever be negative?

No, average speed cannot be negative. Speed is the magnitude of how fast an object is moving, regardless of direction. It's always positive or zero. Velocity, on the other hand, can be negative as it accounts for direction.

8. Why might an object's average speed be greater than its average velocity?

An object's average speed can be greater than its average velocity when the object doesn't move in a straight line or changes direction. This is because speed considers total distance traveled, while velocity only considers net displacement. For example, if you run around a circular track, your average speed is positive, but your average velocity is zero.

9. How can an object have a non-zero average speed but zero average velocity?

This occurs when an object returns to its starting point. The average velocity is zero because the net displacement is zero, but the average speed is non-zero because the object has traveled a distance. An example is running around a track and finishing where you started.

10. Can an object have constant speed but changing velocity?

Yes, this is possible when an object moves in a curved path at a constant speed. The speed remains the same, but the velocity changes because the direction of motion is continuously changing. An example is a car moving around a circular track at constant speed.

11. How can an object have a higher instantaneous speed than its average speed?

An object can have a higher instantaneous speed than its average speed if it varies its speed during the journey. For example, a car might reach high speeds on a highway but slow down in city traffic. The instantaneous speed at its fastest point would be higher than the overall average speed of the entire journey.

12. How does acceleration affect average speed and average velocity?

Acceleration changes an object's instantaneous velocity over time. This can affect both average speed and average velocity. If acceleration is constant, average velocity is the average of initial and final velocities. Average speed, however, depends on the actual path taken and may differ from this average.

13. Why is it incorrect to say "average speed in a particular direction"?

It's incorrect because speed is a scalar quantity that doesn't have direction. When you specify a direction, you're actually referring to velocity. The correct term would be "average velocity in a particular direction."

14. What does it mean when average speed equals average velocity?

When average speed equals average velocity, it indicates that the object has moved in a straight line without changing direction. In this case, the total distance traveled is equal to the magnitude of the displacement.

15. How do average speed and average velocity relate to the slope of position-time graphs?

On a position-time graph, the slope represents velocity. The slope of a straight line from the initial to the final point gives the average velocity. Average speed, however, cannot be directly determined from this graph as it doesn't show the actual path taken.

16. What does a negative average velocity indicate?

A negative average velocity indicates that the object's final position is behind its initial position relative to the chosen coordinate system. It means the object has moved in the direction opposite to what is defined as positive.

17. How does the formula for average speed differ from that of average velocity?

The formula for average speed is (total distance traveled) / (total time taken), while the formula for average velocity is (displacement) / (time taken). The key difference is using total distance versus displacement in the numerator.

18. Why is it important to specify the time interval when discussing average speed or velocity?

Specifying the time interval is crucial because average speed and velocity can vary significantly depending on the chosen interval. A longer interval might mask short-term variations, while a shorter interval might not represent the overall motion accurately.

19. How does changing the reference point affect velocity measurements?

Changing the reference point can alter the magnitude and direction of velocity measurements. Velocity is relative to the chosen frame of reference. For example, a passenger walking in a moving train has different velocities when measured relative to the train versus relative to the ground.

20. How can two objects have the same average speed but different average velocities?

This can happen if the objects travel the same total distance in the same time but end up at different final positions. For example, if two cars drive for an hour at 60 km/h, but one drives in a straight line while the other takes a curved path, they'll have the same average speed but different average velocities.

21. Why might a pilot be more concerned with ground speed than air speed?

A pilot might be more concerned with ground speed because it represents the actual speed relative to the Earth's surface, which is crucial for navigation and estimating arrival times. Air speed, while important for flight dynamics, doesn't account for factors like wind that can significantly affect the plane's motion relative to the ground.

22. Can an object have a higher average velocity than its maximum instantaneous speed?

No, this is not possible. The average velocity is based on the displacement, which is always less than or equal to the total distance traveled. Therefore, the average velocity can never exceed the maximum instantaneous speed achieved during the journey.

23. Can an object's average speed be lower than its minimum instantaneous speed?

No, an object's average speed cannot be lower than its minimum instantaneous speed. Average speed is calculated using the total distance traveled, which includes all instantaneous speeds. Therefore, it will always be between the minimum and maximum instantaneous speeds experienced during the journey.

24. Can an object's average speed be zero if it's in motion?

No, if an object is in motion, its average speed cannot be zero. Average speed is calculated as total distance traveled divided by total time. If there's any motion, there's a non-zero distance traveled, resulting in a non-zero average speed. However, average velocity can be zero even with motion if the object returns to its starting point.

25. How does the presence of traffic lights affect the relationship between average speed and average velocity in city driving?

Traffic lights cause frequent stops and starts, increasing the total time of travel without necessarily increasing displacement. This tends to lower the average speed more significantly than the average velocity. The difference between average speed and the magnitude of average velocity often increases with more traffic lights.

26. Can an object have constant velocity but varying speed?

No, this is not possible. Constant velocity means both speed and direction remain constant. If speed varies, velocity must also change. However, an object can have constant speed with varying velocity if it moves in a curved path.

27. What's the relationship between displacement and distance traveled?

Displacement is the shortest straight-line distance between the initial and final positions, while distance traveled is the total length of the path taken. Displacement is always less than or equal to the distance traveled. They are equal only when the object moves in a straight line without changing direction.

28. Why might GPS navigation systems use average speed instead of average velocity for arrival time estimates?

GPS systems often use average speed for estimates because it accounts for the actual distance traveled along roads, including turns and detours. Average velocity would only consider the straight-line distance between start and end points, which is usually not the actual path taken on roads.

29. Why is it important to consider both average speed and average velocity in analyzing motion?

Both concepts provide different insights into motion. Average speed gives information about how fast an object is moving overall, regardless of direction changes. Average velocity provides information about the overall progress in a specific direction. Together, they provide a more complete picture of the motion.

30. Can an object's instantaneous velocity ever exceed its average velocity?

Yes, an object's instantaneous velocity can exceed its average velocity. This often happens during acceleration or deceleration. For example, a car accelerating from rest will have instantaneous velocities higher than its average velocity over the entire journey.

31. Can an object have zero average velocity but non-zero displacement?

No, this is not possible. If an object has zero average velocity, it means its final position is the same as its initial position, resulting in zero displacement. Average velocity is defined as displacement divided by time, so zero displacement always results in zero average velocity.

32. How does the concept of average velocity apply to objects moving in two or three dimensions?

In multiple dimensions, average velocity becomes a vector quantity with components in each dimension. The magnitude of this vector is the straight-line distance between start and end points divided by time, while the direction points from the initial to the final position.

33. How does air resistance affect the relationship between average speed and average velocity?

Air resistance can cause an object's speed to vary even if it's moving in a straight line. This can lead to a situation where the average speed is less than the magnitude of the average velocity, especially for objects moving through air over long distances.

34. How does the concept of average velocity apply to circular motion?

In circular motion, the average velocity over one complete revolution is zero, because the object returns to its starting point (zero displacement). However, the instantaneous velocity at any point is tangent to the circle and non-zero. This illustrates the limitation of average velocity in describing some types of motion.

35. Why is it incorrect to add average velocities from different time intervals?

Adding average velocities from different time intervals is incorrect because velocity is a vector quantity that depends on both magnitude and direction. The correct way to find the overall average velocity is to calculate the total displacement over the total time, not by adding individual average velocities.

36. How does the concept of average velocity apply to a bouncing ball?

For a bouncing ball, the average velocity over a complete bounce (from release to return to the same height) is zero, as the displacement is zero. However, the instantaneous velocity and average velocity over shorter intervals within the bounce are non-zero and constantly changing.

37. How does the concept of average velocity apply to objects in free fall?

For objects in free fall (ignoring air resistance), the average velocity over any interval is the average of the initial and final velocities. This is because acceleration due to gravity is constant, resulting in a linear change in velocity over time.

38. How does the concept of average velocity apply to a person walking on a moving walkway in an airport?

The person's average velocity relative to the ground is the sum of their velocity relative to the walkway and the walkway's velocity relative to the ground. This illustrates the principle of relative motion and the importance of specifying the frame of reference when discussing velocity.

39. How does the presence of stop signs affect the relationship between average speed and average velocity in residential areas?

Stop signs, like traffic lights, tend to decrease average speed more than they decrease the magnitude of average velocity. They increase the total time of travel without necessarily increasing the total distance or changing the displacement significantly. This leads to a greater difference between average speed and the magnitude of average velocity in areas with many stop signs.

40. Why is it important to distinguish between speed and velocity in describing the motion of weather systems?

Distinguishing between speed and velocity is crucial for weather systems because direction is as important as the rate of movement. The velocity of a storm system, for instance, indicates both how fast it's moving and in what direction it's heading, which is vital for accurate weather forecasting and issuing timely warnings.

41. How does the concept of average velocity apply to a satellite orbiting Earth?

For a satellite in a circular orbit, the average velocity over one complete orbit is zero, as it returns to its starting point (zero displacement). However, its instantaneous velocity is constantly changing in direction (but not magnitude) as it moves in its orbital path. This illustrates how average velocity can sometimes fail to capture the complexity of certain types of motion.

42. Can an object have a constant average velocity but a changing average speed?

Yes, this is possible. For example, if an object moves in a straight line but alternates between fast and slow speeds, its average velocity over the entire journey could remain constant (as it depends only on the start and end points), while its average speed over different intervals would change.

43. How does the concept of average velocity apply to a pendulum's motion?

For a pendulum, the average velocity over a complete swing (from one extreme to the other and back) is zero, as the displacement is zero. However, the instantaneous velocity and average velocity over shorter intervals within the swing are non-zero and constantly changing in both magnitude and direction.

44. Why might a cyclist be interested in both average speed and average velocity?

A cyclist might be interested in average speed to gauge their overall performance and energy expenditure over a route. Average velocity, on the other hand, would be more relevant for understanding their progress towards a destination, especially on a winding route where the straight-line distance differs significantly from the distance traveled.

45. How does the presence of curves in a race track affect the relationship between a car's average speed and average velocity?

Curves in a race track increase the total distance traveled compared to the straight-line distance between the start and finish. This means the average speed (total distance / time) will be higher than the magnitude of the average velocity (displacement / time). The more curves in the track, the greater this difference will be.

46. Can an object's average velocity be zero over a non-zero time interval if it's constantly in motion?

Yes, this is possible if the object returns to its starting point. For example, a car driving around the block and returning to its starting position has zero average velocity over that interval (zero displacement), even though it was constantly in motion.

47. How does the concept of average velocity apply to a boat crossing a river with a current?

The boat's average velocity relative to the shore is the vector sum of its velocity relative to the water and the water's velocity relative to the shore (the current). This means the boat's path through the water may not be the same as its path relative to the shore, illustrating the importance of considering reference frames in velocity calculations.

48. Why might average speed be a more useful measure than average velocity for assessing a delivery driver's performance?

Average speed might be more useful for assessing a delivery driver's performance because it accounts for the total distance traveled, including all stops and route changes. Average velocity only considers the straight-line distance between the start and end points, which doesn't accurately reflect the driver's actual route or effort.

49. How does the concept of average velocity apply to a person on a Ferris wheel?

For a person on a Ferris wheel, the average velocity over one complete revolution is zero, as they return to their starting point (zero displacement). However, their instantaneous velocity is constantly changing in both magnitude and direction as they move in the circular path.

50. Can an object have a higher average speed in one reference frame but a lower average speed in another?

Yes, this is possible due to the relative nature of motion. For example, a passenger walking towards the front of a moving train has a higher average speed relative to the ground than relative to the train. The choice of reference frame can significantly affect speed measurements.

51. How does the presence of traffic congestion affect the relationship between average speed and average velocity in urban commuting?

Traffic congestion tends to decrease average speed more significantly than it affects the magnitude of average velocity. Congestion increases travel time without necessarily increasing the distance traveled or changing the overall displacement. This leads to a greater difference between average speed and the magnitude of average velocity in congested conditions.

52. Why is it important to consider both average speed and average velocity in analyzing the motion of ocean currents?

Both measures provide valuable but different information about ocean currents. Average speed gives insight into the overall rate of water movement, which is important for understanding energy transfer. Average velocity, being a vector quantity, provides information about the direction of water movement and net transport of water masses, crucial for understanding climate patterns and marine ecosystems.

53. How does the concept of average velocity apply to a sprinter running a 100-meter dash?

For a sprinter in a 100-meter dash, the average velocity is simply the total displacement (100 meters) divided by the total time. However, this doesn't capture the complexity of the run, which typically involves acceleration at the start, a period of top speed, and sometimes a slight deceleration at the end. The instantaneous velocity varies throughout the race, while the average velocity gives an overall measure of performance.

54. Can an object's average speed be equal to its instantaneous speed at any point during its motion?

Yes, this is possible. For example, if an object accelerates uniformly from rest, there will be a point where its instantaneous speed equals its average speed for the entire journey. This occurs when the object has covered half the total distance. However, this equality is usually momentary unless the object is moving at a constant speed.

55. How does the concept of average velocity apply to the motion of tectonic plates?

The average velocity of tectonic plates is typically very small in magnitude (a few centimeters per year) but is crucial for understanding long-term geological processes. It represents the overall direction and rate of plate movement, which drives phenomena like continental drift, mountain formation, and earthquake activity. The average velocity in this case is more meaningful than instantaneous measurements due to the extremely slow nature of plate motion.