This article is about the difference between speed and velocity. Speed is the rate of change of distance according to time. It is scalar quantity i.e. speed has magnitude but no direction. Velocity is the rate of change of displacement according to time. It is vector quantity i.e. velocity has both magnitude and direction. Speed is the ratio of distance to time and velocity is the ratio of displacement to time. Speed magnitude is a non-zero positive number while velocity magnitude can be positive, negative, or zero.
Speed & Velocity
What is Speed?
Speed= Distance / Time
- Speed of a body is defined as the distance covered by the body per unit time.
- It determines how fast an object is moving.
- It is the rate of change in distance with respect to time.
- Its SI unit is meter per second (ms-1).
- It is a scalar quantity i.e., it has only magnitude.
- It is positive and non-zero number.
Example
Suppose a truck travels a distance of 300 kilometers in 5 hours. To calculate the speed, use the formula: Speed= Distance / Time
Speed= 300 / 5=60 km/h
Therefore, the truck’s speed is 60 km/h. This value demonstrates the rate at which the car is covering the distance, regardless of the direction.
Types of Speed
The different types of speed are mentioned below:
- Average speed: The ratio of total distance covered by the body to total time is called average speed.
- Relative speed: The speed calculated between two body with respect to each other is called as relative speed.
- Instantaneous speed: The speed of a body at any instant is called instantaneous speed.
- Tangential speed: The speed of the body while moving in a circular path is called tangential speed.
- Rotational speed: The number of rotations of a body per unit time is called rotational speed.
What is Velocity?
Velocity = Displacement / Time
- The velocity of a body is defined as the displacement covered by the body per unit time.
- Velocity describes both direction and speed of an object’s motion.
- It is the rate of change in displacement with respect to time.
- Its SI unit is meter per second (ms-1).
- It is a vector quantity i.e., it has both magnitude and direction.
- It can be positive, negative or zero.
Types of Velocity
The types of velocity are mentioned below:
- Constant Velocity: The velocity which does not changes its magnitude and direction and travels in a straight line is called constant velocity.
- Changing Velocity: The velocity which changes its magnitude or direction, or both is called as changing velocity or acceleration.
- Instantaneous Velocity: The velocity of a body at any instant is called as instantaneous velocity.
- Terminal Velocity: The velocity of the body obtained by falling down due to gravity is called the terminal velocity.
- Relative Velocity: The velocity calculated between two objects in a single coordinate system is called relative velocity.
Example of Velocity
Assume a person walks for 2 hours from point A to point B, which is 6 kilometers west. To calculate the velocity, use the formula: Velocity = Displacement / time.
Velocity = 6km (west) / 2 hours = 3 km/h (west)
Therefore, the person’s velocity is 3 km/h west. This value represents both speed and direction of the person.
Difference Between Speed and Velocity
The difference between speed and velocity are tabulated below:
Characterization |
Speed |
Velocity |
|---|---|---|
| Definition | Speed is the ratio of distance to time. | Velocity is the ratio of displacement to time. |
| Formula | Speed = Distance / Time | Velocity = Displacement / Time |
| Quantity | It is a scalar quantity. | It is a vector quantity. |
| Direction | It does not have direction. | It has direction. |
| Change in | It is a change in distance with respect to time. | It is a change in displacement with respect to time. |
| Magnitude | Its magnitude can be only positive and non-zero. | Its magnitude can be positive, negative, or zero. |
|
Units |
Speed is typically expressed in units such as m/s, km/h, mph |
Velocity share the same units as speed but includes a direction component (e.g. m/s east) |
| Example | A person is riding a bicycle at the speed of 10 km/s. | A person is riding a bicycle with a speed of 10 km/s towards the east. |
Similarities Between Speed and Velocity
The similarities between Speed and Velocity are mentioned below:
- The SI unit for both speed and velocity is a meter per second (ms-1).
- The dimension formula for speed and velocity is [LT-1].
- Both speed and velocity have magnitudes
Conclusion
From the above article, we conclude that speed is the ratio of distance to time and velocity is the ratio of displacement to time. Speed is scalar quantity i.e., it has only magnitude whereas velocity is vector quantity i.e., it has both magnitude and direction. Speed is the change in distance with respect to time and velocity is the change in displacement with respect to time. The magnitude of the speed can only be non-zero and positive. The magnitude of the velocity can be positive, negative or zero.
Difference Between Speed And Velocity – FAQs
1. Define Speed.
Speed of the body is the ratio of the distance to time. It is the rate of change in distance with respect to time.
2. When would you use speed instead of velocity?
Speed is used when we want to know how fast an object is moving, irrespective of the direction.
3. Define Velocity.
Velocity of the body is the ratio of the displacement to time. It is the rate of change in displacement with respect to time.
4. Can you have negative velocity?
Yes, negative velocity means you are moving in the opposite direction. For example, if your velocity is -30 m/s to the east, it means you are moving west at 30 meters per second.
5. Do speed and velocity have the same units?
Yes, speed and velocity are both measured in meters per second (m/s) or kilometers per hour (km/h).
6. State the formula of Speed.
Formula for speed is given by: Speed = Distance / Time
7. State the Formula of Velocity.
Formula for velocity is given by: Velocity = Displacement / Time