Rotatory and Translational motion: A rigid body is made up of a number of particles such that the relative distances of constituent particles remain unaffected under the action of force.
The motion of such a body will be mainly of two kinds:
- Translational Motion
- Rotational (Rotatory) Motion
Rotatory and Translational Motion
In translational motion, all the constituent particles of a body move along parallel straight lines and undergo equal distance in equal time.
Translational motion is progressive motion and every particle is equally effective in determining the motion of the body.
The moving body, in this case, may be treated as a single particle.
The entire mass is assumed to be concentrated at a point, i.e. the center of gravity of the body.
Such a motion may be altered or produced by a single force acting on the body or a set of forces equivalent to a single force.
In rotational motion, on the other hand, the body rotates about a fixed axis.
The different constituent particles of the body have different linear velocities although their angular velocity is the same.
Rotational motion in the stationary object can be produced or altered by a couple acting on the body or a set of couples equivalent to the single couple. This is how we have explained rotatory and translational motion.
Read: Temporal & Spatial Coherence