If the velocity of a body decreases with time, then its final velocity is less than the initial velocity and thus its acceleration is negative. Negative acceleration is called retardation or deceleration. For example, when brakes are applied to a moving truck, its velocity gradually decreases. In other words, it is under retardation.

The table given below shows distance (n cm) travelled by bodies A, B and C. Read this data carefully and answer the following questions. Distance (in cm) covered by different bodies.
Time in (s) | Body (A) | Body (B) | Body (C) |
1stSecond | 20 | 20 | 20 |
2ndSecond | 20 | 36 | 60 |
3rdSecond | 20 | 24 | 100 |
4thSecond | 20 | 30 | 140 |
5thSecond | 20 | 48 | 180 |