* Acceleration is the rate of change of velocity. It describes how quickly the velocity of an object is changing.
* Velocity is a vector quantity, meaning it has both magnitude (speed) and direction.
Here are some examples:
* An object at the peak of its trajectory: Imagine throwing a ball straight up in the air. At the very top of its path, for a brief moment, the ball's velocity is zero (it's stopped before falling back down). However, gravity is still acting on it, causing it to accelerate downwards.
* A car at a red light: A car stopped at a red light has zero velocity. But if the driver presses the gas pedal, the car will accelerate forward even though it's initially at rest.
Key Point: Acceleration is about *change* in velocity, not just the current velocity itself.
