Question

A body is said to be in translational equilibrium if net force is:
A. Unity
B. Zero
C. Maximum
D. Minimum

Answer 1

Hint: Use the basic definition of translational equilibrium which states it is a state in which the body either moves with a constant velocity or the body is stationary. Then, using the relation between force and velocity per unit time, find the net force on the body. Also, Newton's third law of motion gives relation between force and acceleration and eventually velocity. So, substituting velocity in these relations finds the net force on the body.

Complete step by step answer:
There are two common types of motion in physics. They are namely Rotational Motion and Translational Motion. These motions have equilibrium associated with them.
An object is said to be in a translational equilibrium if either the object is not moving or the object is moving with a constant velocity in a straight line.
We know, force is directly proportional to change in velocity per unit time. At translational equilibrium, change in velocity is zero as it is either at rest or moving with constant velocity. As the change in velocity is zero, the net force is also zero. When a body is at equilibrium, the forces cancel out each other.
We can also refer to Newton's first law of motion which states that if no unbalanced force acts on an object then the object does not accelerate and hence its velocity remains constant.
Thus, a body is said to be in translational equilibrium if net force is zero.
Hence, the correct answer is option B i.e. zero.

Note:
Equilibrium does not mean that nothing is happening to the body. It is a state in which some process is happening to the body but a balance is achieved such that there is no change in the state of the body. It is a state in which neither state of the body changes nor its internal energy.