An object is said to be accelerated if there is a change in its velocity. The change in the velocity of an object could be an increase or decrease in speed or a change in the direction of motion. A few examples of acceleration are the falling of an apple, the moon orbiting around the earth, or when a car is stopped at the traffic lights. Through these examples, we can understand that when there is a change in the direction of a moving object or an increase or decrease in speed, acceleration occurs.