Difference between Speed and Velocity

 

Imagine you are travelling in a car.

You were sleeping soundly and suddenly you wake up.

You realise the car is moving.

You look at the speedometer and  the pointer shows 50 km/hr

Figure 1 Speed

But you don't know where the car is or in which direction it is moving.

This data is called speed.

It denotes the change in position of the object, but the reference is missing.

 

Now you open an App that shows the coordinates and direction of the car, along with the Speed.

All this data is now called velocity.

Speed is the time rate at which an object is moving along a path, while velocity is the rate and direction of an object's movement.

Speed = Distance/Time

Velocity = Displacement/Time

·         Speed is the distance covered by an object in unit time whereas velocity is the displacement covered in unit time. 

 

·         Difference between distance and displacement- Distance, which is a scalar quantity covered by an object, whereas, a displacement which is a vector quantity deals with the change in the position of the object. The distance can never be zero, whereas, displacement can become zero.

 

If a runner runs on a circular track from point A back to point A, the distance he covers will be the perimeter or a circle, but the displacement will be zero.

 

Summary of Differences

·         Speed is a scalar quantity and velocity is a vector. 

·         Speed only determines the magnitude that is how fast is a body moving whereas velocity determines the direction also that is in which direction the body is moving.

·         Speed is the rate of change of distance whereas velocity is the rate of change of displacement. 

·         Speed can never be zero but the velocity can be positive, negative or zero. This is the difference between speed and velocity. 

·         An object can possess the same speed and different velocities. Speed may or may not be equal to velocity.

·         Speed and velocity both are measured in m/s

·         The speed at a particular instant is called instantaneous speed. Like it is shown on the Speedometer.

 

If a car is driven on a circular racetrack of 2 km for 8 laps in 10.0 min, what is the average speed? What is the average velocity? Does that mean that the average velocity is zero m/s? Because the runner ends on the point where he started?

The Earth revolves around the Sun, hence Earth's orbital speed averages 29.78 km/s (107,208 km/h; 66,616 mph). Velocity will be zero.

Also Read :

Difference between Rotate and Revolve

 

Quiz

What is the unit of measurement used in physics for speed?

Velocity is a vector measurement because it also has a ________.?

The speed of an object at a specific moment in time is called,……..?