Question

Define acceleration. When is an object said to be decelerating?

Answer 1

1. Acceleration is the change in velocity in unit time or the rate of change of velocity.
2. $Acceleration=\frac{changeinvelocity}{timetakenforthechange}$
3. The SI unit of acceleration is a meter per second per second $(\raisebox{1ex}{$m$}\!\left/ \!\raisebox{-1ex}{$s^{2}orm{s}^{-2})$}\right.$.
4. If the velocity of an object decreases, the acceleration is negative and the body is said to be decelerating.
5. Negative acceleration is also known as deceleration or retardation.