Question

How do you describe motion?

Answer 1

Motion is the change in position of a body with time. If the position changes with time, the body is in motion otherwise stationery. The motion is described using various factors. Also there are certain laws laid down in order to analyse the motion of an object.

Complete answer:
Motion of a body is simply the change in the position of a body with time. If the position is continuously changing with time, the body is in motion otherwise, the body is at rest or stationery.
The motion is described in terms of distance, displacement, speed, velocity, acceleration etc.
The scalar quantities like distance, speed etc are used to describe the magnitude with which a body changes its motion while the vector quantities like displacement, velocity, acceleration etc are used to describe the magnitude as well the direction with which a body changes its position.
The motion can also be described with respect to a frame of reference. If position changes with respect to the frame, the body is in motion otherwise stationery.
Some important laws used to describe motion are Newton’s three laws of motion.
The first motion states that an object will continue to remain in its state of rest or motion unless compelled to change its state.
The second law of motion states that the force acting on a body is the product of its mass and acceleration.
The third law of Newton states that every action has an equal and opposite reaction.
Therefore, the motion of a body is described by various factors.

Note:
The magnitude of a scalar is represented by the unit while the direction of a vector is represented by a vector in space. A body does not change its state (according to Newton’s first law) due to inertia. According to the third law, the force acting on two bodies are different but they have the same magnitude and act in opposite directions.