# Average Speed and Average Velocity

To understand the whole structure and meaning of the two terms (average speed and average velocity), we need to study some basic concepts before going into detail. The following are some of them -

1. Distance Traveled: This is the measure of total distance covered by the object or substance.
2. Time Taken: If work has to be done, there must be some amount of time needed to be taken to finish that particular work. So, this is simply termed as the time taken.
3. Displacement: If an object needs to be moved, there must be a starting point and an ending point for that. This shortest distance between the two points where the object is moved is defined as displacement.
4. Speed: Speed is the distance traveled by any particular object in unit time. It can be represented as a scalar quantity which indicates that its direction is not specified. Speed is the particular rate at which an object covers a certain distance or in simple terms, it indicates how fast an object can move from one place to another.
5. Velocity: It is defined as the rate of change of displacement of a particular object with respect to time in a particular direction. Velocity can be represented as a vector quantity which indicates that it contains some specific direction. For example, when a child starts to walk for a certain distance and decides to go back to his original position, this walking motion ends up with zero displacement, and hence, zero velocity. Moreover, velocity is considered as the rate of displacement and if that child wants to increase his velocity, he should consider maximizing the displacement from his starting point. This is because velocity is a vector quantity and only the displacement is taken into account to calculate the amount of distance moved or walked.

These concepts are extensively discussed in NCERT Solutions Class 9 Science Chapter 8 Motion.

One significant difference can be seen between speed and velocity from the above statements. It clearly states that speed does not take direction into account, as it is a scalar quantity whereas velocity does consider direction, as it is a vector quantity. Furthermore, speed relies only on the distance covered while velocity depends on displacement.

Now that we deeply understand each term, we can head into understanding what exactly is average speed and average velocity.

## Average speed

Average speed is the entire distance covered by that object with respect to the time which is taken to finish the movement. It provides an idea of the average rate at which the distance is covered. For example, imagine an object has a speed of 30 km/hour, it simply indicates that the position of that object is capable of changing 30 km for every hour on average. Its SI unit is m2 / s. Given below is the formula which is derived in order to calculate the average speed of any object,

### S = d/t

Where,

S = Average speed

d = total distance

t = total time taken

which turns the formula into,

## Average velocity

Average velocity can be described as the occurrence of displacement with respect to the original position of any particular object in a specific time period. In simple terms, average velocity is the rate at which an object can make displacements in accordance with time. The SI unit of average velocity is also m2 / s like average speed. Furthermore, average velocity can also be termed as the ratio of total displacement to total time taken for any particular object.

Formula for average velocity is given below,

### V = D/t

Where,

V = Average velocity

D = total displacement

t = total time taken

which turns the formula into,

### Average Velocity = displacement/time

The average velocity’s direction is the same as its displacement direction. Though an object contains a fluctuating speed that changes its magnitude quite often, its direction would remain the same as of displacement’s direction. It can be seen that the magnitude of average velocity is almost always the same or a bit less than that of the average speed. This is because displacement can be seen as either less or equal to the total distance which is being covered.

## Main similarity of average speed and average velocity

One major similarity between these two is that the SI unit as well as other main units which are quite the same for both average speed and average velocity.

## Main difference between average speed and average velocity

A major difference between both of them would be, the average speed is a scalar quantity whereas average velocity is a vector quantity.

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