Here's why:
* Speed is a scalar quantity, meaning it only has magnitude (how fast something is moving).
* Velocity is a vector quantity, meaning it has both magnitude and direction.
When a body moves in a straight line, its direction of motion remains constant. In this case, the magnitude (speed) and direction of the body's motion are the same, making its velocity and speed equal.
For example:
* If a car is traveling at 60 mph due east, its speed is 60 mph, and its velocity is 60 mph due east.
* However, if the car turns a corner, its speed might remain 60 mph, but its velocity changes because the direction of motion changes.
