* Speed is a measure of how fast something is moving. It's a scalar quantity, meaning it only has magnitude (e.g., 10 meters per second).
* Acceleration is the rate of change of velocity. Velocity is a vector quantity, meaning it has both magnitude and direction (e.g., 10 meters per second east).
Here are some examples:
* A ball thrown straight up in the air: At the very top of its trajectory, the ball momentarily stops moving (speed is zero) before falling back down. However, gravity is still acting on it, meaning it has an acceleration of 9.8 m/s² downward.
* A car at a stoplight: The car is not moving (speed is zero), but the driver might press the gas pedal, causing the car to accelerate.
* An object at the top of a roller coaster loop: The object momentarily stops moving (speed is zero) before accelerating down the loop.
In essence, acceleration is about the change in velocity, not just speed. It's possible to have a change in velocity (acceleration) without a change in speed if the direction of motion changes.
