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Question 1: (a) What are different types of motion?
(b) Explain why the concept of distance/displacement, speed/velocity, acceleration and time are called parameters of motion.


We know that a body is in motion if it changes its position relative to its surrounding. In Physics, we study motion and force under mechanics. Mechanics is further subdivided into Kinematics and Dynamics.

  1. Kinematics explains motion without making any reference to force.
  2. In Dynamics, we study motion with reference to its cause, i-e, force.

Types of motion

There are three types of motion.

(1) Translatory Motion

In translatory motion, every particle of the body moves parallel to each other along the path of motion. The path of motion may be straight or curved.

(2) Rotatory Motion

In rotatory motion every point of the object moves around a fixed point or axis of rotation.
Motion of the wheels of a car, moving blades of the fan etc. are examples of rotatory motion.

(3) Vibratory Motion

To and fro motion of a body about its mean position is called vibratory motion. Examples of such motion are motion of a body attached to a spring; back and forth motion of a swing, motion of the wire of a violin etc. (What about the motion of our chest when we breathe)?


The concepts of distance/displacement, speed/velocity, acceleration and time are called parameters of motion because they enable us to describe the motion qualitatively as well as quantitatively. The qualitative and quantitative description of motion means that they enable us;

  1. To define various quantities as in motion and at rest, and to differentiate between them.
  2. To know about their exact nature as scalar or vector.
  3. To derive the magnitude and direction of a particular quantity varying with time.
  4. To derive equations of motion that fully describes the quantities during the motion of a particular object.

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