Question

The motion in which all the points of a moving body move uniformly in the same line or direction is known as:
(A) Rolling
(B) Rotatory
(C) Both A and B
(D) Translatory

Answer 1

Hint
Translatory motion is only the type of motion in which all the points of the body move with same velocity (uniformly) and they trace the same parallel paths either straight line or a curve.

Complete step by step answer
All different types of motion in the options are described below:
1. Translatory motion: It is the type of motion in which all the points of a rigid body travel the same distance in a given time, i.e. velocity of every point on the object is the same. It means all the points trace the same straight path or curve path depending upon the motion is rectilinear or curvilinear motion.
Examples: like a block sliding on the floor, body of the car moving on the road, a ball thrown up in air at an angle etc.
2. Rotatory motion: It is the type of motion in which the body moves about an axis. In this type of motion all the points in a body cover different distances because they all are moving in a circle of different radii.
Examples: Blades of a rotating fan, a merry-go round etc.
3. Rolling motion: It is the combination of both rotatory motion and translatory motion. Here, all the points trace different paths and they have different velocity.
Examples: Wheels of any vehicle moving on a road.
From the above discussion it is clear that it is only the translatory motion in which all the points of the body move uniformly (same velocity) in the same line.
Hence, option (D) is correct.

Note
In rotatory motion, some points cover the same distance but some not. For example: if we only consider the outer points of a rotating blade, they are moving on the same circle and distance, and also if we only consider the inner points of the blade, they are also moving the same circle and distance. But if we consider both the outer points move a longer distance than inner points.