What do you mean by motion in one direction?

Hint:Motion is something that tells us about the position of the body. When the position of the body changes we say that it is moving. A body can have various types of motion. one of those is motion in one direction.

Complete answer:
When the position of a body changes with time, we say that the body is in motion. The motion is influenced by the net force acting on the body. Therefore, the motion of a body depends on the net force on the body.

Hence, there exist more than one type of motion. One type of motion is motion in one direction. When a body moves along an imaginary straight line towards a single direction, its motion is said to be in one direction. This means that the body moves in a single direction for all the time.

When the body moves in one direction, its motion is called as rectilinear motion. A body moves in rectilinear motion when a constant net force acts on the body if the body is at rest initially.

Examples of motion in one direction are the motion of a train travelling on a straight track, motion of a body in free fall and the upward motion of a ball thrown vertically upwards.

Note: Other than motion in one direction, a body can be in circular motion and oscillatory motion. When the body travels along a circular path, its motion is said to be circular. When the body performs to and fro motion, its motion is said to be oscillatory.