Unit 1
AVERAGE ACCELERATION =
CHANGE IN VELOCITY TIME INTERVAL
AVERAGE ACCELERATION
The AVERAGE ACCELERATION of an object is defined as the net change in its velocity per unit time:
The SI unit of acceleration is m / s /s and is written as ms −2. You must always write the DIRECTION of acceleration.
Quite often we wish to know the acceleration of an object at a given instant of time. Then we need to define its instantaneous acceleration. We shall give its precise definition in the next section after you have learnt the mathematics needed. For the moment, you can understand INSTANTANEOUS ACCELERATION as acceleration at any given instant of time.
You may have heard sports commentators saying that a person is accelerating if he or she is moving fast. But acceleration has nothing to do with going fast. An object could be moving very fast (at a high CONSTANT velocity), and still not be accelerating. ACCELERATED MOTION MEANS THAT THE OBJECT’S VELOCITY IS CHANGING. If its velocity does not change with time, then the object is not accelerating. When an object slows down, it is said to be DECELERATING.
For example, when a car or bus starts, it has a finite acceleration as its velocity changes from 0 to some value in a given time. But when it moves with a constant speed/velocity, its acceleration is zero.
CONSTANT VELOCITY MEANS ZERO ACCELERATION.
CONSTANT ACCELERATION MEANS THAT THE CHANGE IN VELOCITY IS CONSTANT.