You might come across the term ‘speed’ almost every day, no matter to which walk of life you belong to. Yet, what does ‘speed’ actually mean in terms of physics? Is it any different from the sense you generally use it in? Moreover, what is the SI unit of speed? This article will help you answer all the questions that you have in mind regarding this topic.

In the field of physics, speed refers to the rate at which an object moves. More specifically, this term implies the distance that an object travels with respect to time. You witness moving objects daily, such as a car, a cycle, or even while walking. Thus, speed is the measurement of the distance that a body covers within a particular time.

When a body covers greater distance within a specific amount of time, you can say that it has a high speed. On the other hand, when that very body covers a short distance at the same time, the speed is low.

Every measurement requires an SI unit so that it becomes easy to distinguish it from the rest. A simple numerical expression is ambiguous and vague, and it could mean a thousand things. Therefore, you will need a basic unit of speed that differentiates it from other measurements.

Now, if you are asking what the basic unit of speed is, here is the answer –

Meter per second is the SI unit of speed. This unit of speed signifies as to how many meters an object can travel within a second. Say, a body travels 10 meters in a second. In that case, the speed of the body is 10 meters per second.

The SI unit of speed is written as m/s.

Now that you know that speed is the distance that an object travels within a specific time, you must also note why the unit of speed is a derived unit.

The definition of speed in mathematical terms is expressed by the following formula which is also used to calculate the same.

ν = d/t

Where '' V stands for speed, ‘d’ means distance, and ‘t’ implies time.

Suppose that an object covers 50 meters at a time of 5 seconds, then –

ν = 50 metres/ 5 seconds = 10 meters/second or 10 m/s. Therefore, the SI unit of speed is 10 m/s for this object.

Also, speed also possesses a dimensional formula, which is M0.L1.T-1.

You can also express the SI unit of speed in terms of the CGS system, or centimeter-gram-second system. In that case, cm/s or cm s-1 signifies the speed of a moving object.

Suppose that an object moves 100 meters in 20 seconds. Consequently, the speed becomes 5 m/s. However for CGS unit, you will have to convert 100 meters into cms.

1 m = 100 cm

Therefore, 100 m = 100 X 100 cm = 10,000 cm. Thus, the CGS expression of speed in this case becomes-

ν = 10,000 cm/20 seconds = 500 cm/s or 500 cm s-1.

Keep in mind the following interesting facts involving speed –

The speed at which light travels is 299,792,458 m/s.

The speed of sound in dry air is 343.20 m/s.

You would have to travel at a speed of 11.2 km/s (or 11200 m/s) to escape the gravitational pull of our planet.

Now that you know that the SI unit of speed is m/s, browse on our website to learn even more about the intriguing properties of speed and other related concepts.

You can even download our Vedantu app for an interactive and personalized learning experience.

FAQ (Frequently Asked Questions)

1. What is Speed?

Ans. Speed is the expression of the distance that a moving object travels within a certain time.

2. What is the SI Unit of Speed?

Ans. The SI unit of speed is metre per second which is expressed as m/s or m s^{-1}.

3. What is the CGS Unit of Speed?

Ans. The CGS unit of speed is centimetre per second which is expressed as cm/s or cm s^{-1}.