* Speedometer: This instrument measures the speed of the car. Speed is a scalar quantity, meaning it only tells you how fast the car is moving. It doesn't indicate the direction of travel.

* Velocity: Velocity is a vector quantity, meaning it includes both speed and direction. So, while the speedometer tells you how fast the car is going, it doesn't tell you where it's going. To know the velocity, you'd need to know both the speed and the direction of travel.

Example:

* A car traveling at 60 mph has a speed of 60 mph.

* If that same car is traveling 60 mph north, it has a velocity of 60 mph north.

In Summary:

* Speed: How fast something is moving.

* Velocity: How fast something is moving and in what direction.

A car's speedometer only measures speed. To determine the car's velocity, you'd need to know both the speed and the direction of travel.