Question

Retardation means
A. negative acceleration
B. positive acceleration
C. zero acceleration
D. none of these

Answer 1

Hint: Recall the concept of acceleration. Remind all the terms in the given options and check any of these terms means retardation. The positive acceleration is written with the positive sign and the negative acceleration is written with negative sign.

Complete step by step answer:
The velocity-time graphs representing the different types of acceleration are as follows:

An acceleration of an object is the change in velocity of the object.
The velocity of the object may increase or decrease.
If the initial velocity of the object is less than the final velocity then the velocity of the object increases.
If the velocity of the object increases then the object is said to have positive acceleration with the positive sign and the meaning of retardation is decreased.
Therefore, retardation does not mean positive acceleration.
Hence, option B is incorrect.

When an object is at rest or in uniform motion, the velocity of the object remains the same. The change in velocity of the object is zero. Hence, the object at rest or in uniform motion has zero acceleration.
Therefore, the retardation does not mean zero acceleration as and the meaning of retardation is decreased.
Hence, the option C is incorrect.

When the initial velocity of the object is less than the final velocity of the object, then the velocity of the object decreases.
If the velocity of the object decreases then the object is said to have a negative acceleration and the meaning of retardation is decreased.
Therefore, retardation means negative acceleration.
Hence, the correct option is A.

So, the correct answer is “Option A”.

Note:
The students may get confused between the uniform acceleration and positive or negative acceleration. The acceleration is uniform if the velocity is increasing or decreasing at a constant rate. Both the positive and negative accelerations may be uniform if the velocities are increasing or decreasing at constant rate.