Acceleration is the rate at which an object changes its velocity. When a car speeds up from a stoplight, it is experiencing acceleration. This change can happen in different ways: an object can speed up, slow down, or even change direction. For example, when a roller coaster goes down a steep hill, it accelerates rapidly due to gravity. In physics, acceleration is measured in meters per second squared (m/s²). If a bicycle rider pedals faster, they are accelerating. Understanding acceleration helps us grasp how forces, like friction or gravity, affect movement in our everyday lives, from driving a car to playing sports.