Difference between Speed and Velocity
We all have heard many terms like inertia, gravity, speed, velocity, etc., in our physics lectures. These terms are used to measure certain things, and all of them have certain formulas as well. So, today we will discuss some points regarding speed and velocity. Now you must be wondering what does speed and velocity means, what the formulas are, and how they are different from one another.
In simple terms, speed is defined as the distance covered by an object, whereas velocity is defined as the change in position of an object. Well, no doubt they have certain differences, and they have different formulas. So, let's discuss them separately. Speed and Velocity are one of the interesting topics in physics.
S.NO. 
SPEED 
VELOCITY 
1. 
Speed is defined as the distance covered by a particular object. 
On the other hand, velocity is defined as the change in position of an object from point A to point B. 
2. 
Speed is a scalar quantity and such quantities do not depend upon the distance. 
Velocity is a vector quantity, i.e., a quantity having direction and magnitude. To measure the motion of an object, a vector quantity is required. 
3. 
An object's speed cannot be zero or negative. It is only positive. 
An object's velocity can be negative, positive, or zero, depending upon the rate at which it is moving. 
4. 
Even if an object changes its direction, the speed is still to be counted. 
The velocity of an object automatically changes with the change in direction. Thus, an object must move in a particular direction. 
5. 
Well, speed can or cannot be equal to velocity. 
On the other hand, velocity is equal to the speed, i.e., an object may move at a certain velocity, but the speed at which it is moving must be the same. 
6. 
The SI unit of speed is m/s, i.e., meter per second. 
The SI unit of Velocity is also m/s. 
7. 
The formula for speed is:
V= d/ t.
In the above formula, 'V' is the average speed, 'd' is the distance travelled, and 't' is the time taken to cover up the distance. 
The formula for velocity is:
V = △x/△t.
In this formula, V is the average velocity, '△ t' is the time taken, and ' △x' is the displacement. 
8. 
Speed lays emphasis on the motion of an object, i.e., the rate/ speed at which an object moves. 
On the other hand, velocity lays emphasis on how fast an object moves along with the change in position. 
9. 
Speed is calculated as the distance travelled in per unit of time. 
Velocity is calculated when displacement takes place in an object in per unit of time. 
10. 
Example:
 A person driving a car at a speed of 70 m/s.
 A student cleaning his/ her room within 10 minutes.
 Ferrari or Jaguar runs at a rapid speed.

Example:
 A person driving a car at a velocity of 70 m/s in the east direction.
 Earth moves around the sun at a certain velocity.
 A ball being dropped from top to the bottom.

So, these are some fundamental differences between speed and velocity. Both speed and velocity are used to measure the change in motion of an object. The major difference between these terms is that of the direction. Speed doesn't include direction, while velocity includes moving at a certain speed along with a particular direction. Speed has no magnitude, but velocity has both direction and magnitude. Now, there are four kinds of speed that are used to measure an object's motion from one point to another.
 Uniform Speed: Uniform Speed is defined as the speed at which an object has the same time interval and the distance. The time taken and distance covered is equal in uniform speed.
 Variable Speed: Variable Speed is defined as the speed wherein an object covers different distances at the same time intervals. The distance covered is different, and the time intervals are the same.
 Average Speed: Average Speed is defined as the speed wherein a ratio of distance travelled and time taken to travel the distance by an object is recorded. Average Speed is also called as the uniform speed.
 Instantaneous Speed: When an object moves at a variable speed (an object covering different distances at the same time intervals), the speed of that object is called instantaneous speed.
So, these are the four kinds of speed in physics. Well, apart from speed, there are certain types of velocity as well. There are four kinds of velocity.
 Constant Velocity: When an object doesn't change in speed or direction, then it is called constant velocity. An object moving at a constant speed has constant velocity.
 Changing Velocity: When an object changes its speed and direction over a certain period of time, it is called changing velocity. A change in an object's velocity is measured through acceleration. For instance, in the solar system, comets and asteroids change their speed and direction. They are affected by the change in gravity.
 Instant Velocity: Instant Velocity is defined as the velocity wherein an object changes its speed and direction quickly. Instant velocity is a method used for measuring the changes in the velocity of a particular object.
 Terminal Velocity: When an object falls freely from the atmosphere, then its velocity is called as the terminal velocity. An object falling from the atmosphere will have air resistance. The air resistance is caused by gravity, and the force upon the object is called terminal velocity.
So, these are the four kinds of velocity which are used to measure the change in speed as well as direction. Velocity includes both magnitude and direction. There are two kinds of motion in velocity, i.e., accelerated motion and constant velocity motion. Both are used to measure the change in velocity.
Speed and velocity are the most interesting topics in physics. Both are different in their own sense. The differences between them have already been given above. One of the major differences between them is of the magnitude. Speed only has direction and doesn't have any magnitude, while velocity has both direction and magnitude. Thus, both speed and velocity are important topics that are used to measure the change in motion of an object.
