The key difference between speed and velocity is that speed is a scalar quantity representing the rate of motion, while velocity is a vector quantity that includes both speed and direction of motion.
What is Speed?
Speed is a measure of how quickly an object moves, regardless of its direction. It is a scalar quantity, which means it only has magnitude (numerical value) and no specific direction associated with it. In other words, speed tells you how fast something is moving, but it doesn’t provide any information about the path or route taken. It is calculated by dividing the distance traveled to the time taken.
Speed = Distance / Time
For example
if a car covers 100 kilometers in 2 hours, its speed is 50 kilometers per hour (50 km/h).
What Is Velocity?
Velocity is a vector quantity that describes the rate of change of an object’s position with respect to time. It includes both the magnitude (speed) of the motion and the direction in which the object is moving. In other words, velocity not only tells you how fast something is moving but also in which specific direction it is moving. It is represented as a combination of a numerical value and a unit of measurement along with a direction.
Velocity = Displacement / Time
For example
if a car is moving eastwards at a speed of 50 kilometers per hour, its velocity is 50 km/h east. If the car changes its direction and starts moving northwards while still maintaining a speed of 50 kilometers per hour, its velocity would change to 50 km/h north.
Velocity takes into account the concept of both speed and direction, providing a more comprehensive description of an object’s motion compared to just speed.
Speed vs Velocity
The primary difference between speed and velocity is given below:
| Speed | Velocity | |
| Definition | The rate of change of distance over time. | The rate of change of displacement over time. |
| Scalar/Vector | Scalar quantity (magnitude only). | Vector quantity (magnitude and direction). |
| Formula | Speed = Distance / Time | Velocity = Displacement / Time |
| Symbol | �v | �v |
| SI Unit | meters per second (m/s) | meters per second (m/s) |
| Direction | Speed does not consider direction. | Velocity includes direction. |
| Average vs Instant. | Can be average or instantaneous speed. | Can be average or instantaneous velocity. |
| Example | A car moving at 60 km/h. | A car moving at 60 km/h eastward. |
| Path | Speed doesn’t consider the path taken. | Velocity considers both magnitude and direction of motion. |
| Changes | If speed changes, only magnitude changes. | If velocity changes, magnitude or direction can change. |
| Graphical | Represented by a scalar value on a graph. | Represented by a vector arrow on a graph. |