Question

A couple produces:
(A). No motion
(B). Linear and rotational motion
(C). Purely rotational motion
(D). Purely linear motion

Answer 1

Hint: Motion is the action acting on the object which results in producing the movement of the object. When the object moves in the straight path, the motion is known as the translational motion. When the object is moving in the circular path around the same point, motion is known as the rotational motion.

Complete step-by-step answer:

Consider a rod having length l is allowed to move by both your hands. One hand applies force on one of the ends of the rod, while another hand applies force on the other hand. These two forces are having equal magnitude and direction of the forces are opposite.

These two forces cause rotational movement of the object. This is known as a couple.

The mathematical expression of the couple of force is given as:
$\tau =Fr$

Where, F is the force and r is the distance
The resultant force acting by the couple is zero. So, there is no linear movement of the object.

Thus, the couple produces pure rotational motion of the object.

Correct option is C.

Note: Couple is the word used for the pair of any quantity. The couple of the force means there are two forces acting on the object. The forces acting on the object are equal in the magnitude and opposite in the direction. So, the object rotates. Couple is not a force; it is the product of force and distance.