Here's why:
* Velocity is a vector quantity, meaning it has both magnitude (speed) and direction.
* Speed is the magnitude of velocity, meaning it's only concerned with how fast something is moving.
Example:
Imagine a car driving at a constant speed of 50 mph.
* Scenario 1: Constant velocity - The car is driving straight down a road. Its velocity is 50 mph east (or any other direction).
* Scenario 2: Changing direction, constant speed - The car makes a turn and is now driving at 50 mph northeast. The speed is still 50 mph, but the direction has changed, meaning the velocity has changed.
Therefore, changing the direction of motion changes the velocity (because it's a vector), but not the speed (which is only the magnitude of the velocity).
