Question

If a body undergoes retardation, its velocity will
A. Increases
B. Decreases
C. remains same
D. May increase or decrease

Answer 1

In physics, as we know that Acceleration is the rate of change of velocity. Usually, it means that the velocity of a body is changing from time to time and this rate of change can be positive or negative as well, depending upon the initial and final magnitudes of velocities in given time.

Complete answer:
Firstly we need to understand the concept of acceleration briefly. Suppose a body is moving uniformly with a constant velocity then, according to the definition of acceleration, the rate of change of velocity is zero so it's called body has zero acceleration.

Secondly, if we assume body has a velocity of ${v_1}$ at given time and velocity ${v_2}$ after some time, and we have given that ${v_2} > {v_1}$ then the change in velocity over given time will be positive hence, it’s called positive acceleration of a body.

Now, In same case if we have given that ${v_2} < {v_1}$ and we find the rate of change of velocity over given time then the magnitude of acceleration will be negative , hence it’s called negative acceleration of a body and this negative acceleration is called retardation.So, retardation is nothing but a negative acceleration which means the velocity of a body gets decreased while having retardation.

Hence, the correct option is B.

Note: Acceleration and retardation both terms are similar with respect to mathematical formulas but retardation is negative which implies that the velocity of a body is decreasing with time and remember, the magnitude of acceleration and retardation may be equal in some cases but retardation will have a negative sign.