Question

A helical spring is stretched by a force, the resultant strain produced in the spring is:
A. Volume strain
B. Shear strain
C. Longitudinal strain
D. All of the above

Answer 1

Hint: Strain is defined as the ratio of change in dimension to the original dimension. It gives the measure of the deformation of the body under force. It is of many types. Based on type of stress, strain can be defined. The strain produced by longitudinal stress (acting along the length) is called longitudinal strain whereas if there is a change in the shape as well as dimensions of a body, the strain is called shear strain and the force producing this strain is called shear strain.

Complete step-by-step answer:
When a body is subjected to a force, it undergoes a change in either shape or dimensions or sometimes both.
Volume strain is a strain in which the whole volume of a body gets compressed, mainly by the application of pressure. For example when a block is placed inside the water, it’s volume reduces by some amount.
Shear strain is a strain in which both shape and dimensions of the body change. For example when a sponge is acted upon a tangential force, it gets bent.
Longitudinal strain is a strain in which the length of a non-rigid material rod increases on application of force.
Now, in spring, when force is applied onto it, it undergoes change in both shape and size. Hence it can be said to undergo shear strain.

So, the correct answer is “Option B”.

Note: When we observe the shape of spiral spring minutely, we can see that the spirals of the spring are coming closer. Hence the change in shape is observed. Also when a spring is pressed, it reduces its length. Thus change in length is also observed. This completely suggests that the strain produced is shear strain.