Difference Between Speed and Velocity

Difference Between Speed and Velocity: Speed and velocity are one of the most important topics in the study of Physics. Sometimes, students get puzzled by the terms speed and velocity. They apply these terms interchangeably. Speed and velocity both are distinct terms. There is always a common question being asked in board and competitive entrance examinations like IIT-JEE, NEET, etc. that is what is the difference between speed and velocity? You apply these speed and velocity terms in day-to-day life. These terms are generally used in the study of Mathematics and Physics. In this article, we describe the concept of speed and velocity, the definition of speed and velocity, the types of speed and velocity, and the difference between speed and velocity.

Speed and Velocity Overview

Speed refers to the travelled distance by a person or an object per unit of time. It is to be noted here that speed doesn’t consider the direction of the moving object. It means that it doesn’t follow direction but only magnitude. Hence speed is considered a scalar quantity. However, velocity refers to the rate of change of displacement. Velocity considers not only magnitude but also the direction of the moving object. So it is considered a vector quantity. As we know displacement is already a vector quantity and distance is a scalar quantity.  For example, Ram is driving his car in Udaipur city at 65 kmph and on another side, Shyam is driving his car in the west of Udaipur city at 75 kmph. Here, it seems both trips are similar in their own way but there is a major difference in both trips as per the view of the physics concept. This is the direction involved in the second trip that tells not only about the magnitude but also its direction. We will elaborate on the difference between speed and velocity completely in this article. It will also help you to know why both speed and velocity are available in the study of physics. 

Definition of Speed 

Speed is defined as the rate of time period at which a person or an object moves along a path and covers a particular distance.  It does not count the direction of the moving person or object. It is called a scalar quantity in Physics. The mathematical calculation for measuring speed is not complicated but rather simple and straightforward. The average speed of a person or an object can be measured by dividing the covered distance by the time period in which the person or object travels that distance. As per the eminent scientist Galileo, speed is a term denoting the covered distance per unit of time. Let us consider that a man drives his car and travels a large distance in comparison to another man who travels by bicycle at the same time. It is due to the more speed travelled by car as compared to that by bicycle. Hence it is concluded that speed is only the magnitude portion of the velocity.

Speed = Distance / Time

The measuring SI unit of speed is meters per second (m/ s).

Types of Speed 

Speed is of two types mainly as follows. 

1. Uniform Speed- If the distance covered by an object or a person is the same in an equal time interval then that speed is called the uniform speed.
2. Non-Uniform Speed: If the distance covered by an object or a person is not the same in an equal time interval then that speed is called the non-uniform speed.

Definition of Velocity 

Velocity is defined as the rate of time period at which a person or an object moves along a path and covers a particular distance with the consideration of the direction of the moving body. It does count the direction as well as the magnitude of the moving person or object. It is called a vector quantity in Physics. The mathematical calculation for measuring velocity is relatively complicated. The average velocity is measured by dividing the change in position (Δr) by the change in the time period (Δt). Velocity is considered the first derivative of the position with respect to the time period.  In simple words, velocity refers to the rate of the positional change of the person or object with respect to time. 

Velocity = Displacement / Time = (Final Point - Initial Point) / Time

The measuring SI unit of velocity is the same as that of speed i.e. meters per second (m/ s).

Types of Velocity 

Velocity is of three types mainly as follows.

1. Constant Velocity- If the velocity is not changed with the direction and speed and it follows a straight line then that velocity is known as constant velocity. 
2. Changing Velocity- If the velocity is changed with the speed and direction or it changes either of them then that velocity is known as changing velocity. It is also considered acceleration. In the case of changing speed and direction at a particular time then that velocity is called Instantaneous Velocity.
3. Terminal Velocity: If gravity takes over a body and makes that body to be fallen down towards the earth and passed through the atmosphere then the constant velocity attained by that fallen body will be known as the terminal velocity.  

Difference Between Speed and Velocity 

The two terms speed and velocity are different from one another. The detailed comparison between speed and velocity is explained here below so that you can easily understand the terms speed and velocity in a better way.