Question

A long piece of rubber is wider than its thickness. When its stretched in length by some amount
A. Its thickness decreases but its width increases
B. Its thickness decreases but its width is constant
C. Its thickness increases but its width decreases
D. Both its thickness and width decrease

Answer 1

Let the rubber piece be considered to be cuboidal in shape for simplicity.
The volume of a cuboid is given by the product of its 3 dimensions which are length, breadth and height.
i.e. $V=l\times b\times h$

Complete step by step answer:
Since the given piece of rubber has both width and thickness, it will have the dimensions of length(l), breadth(b) and height(h).
It will be having a constant mass, and since the rubber piece is a solid material, it will also be having a constant volume.
The volume of the given rubber material is given by:
$V=l\times b\times h$
Since the volume(V) is to be kept constant despite an increase in the length(l) in the RHS, the other 2 terms, breadth and height will accordingly decrease in order for the equality to persist.
Hence, the correct option will be option D.) Both its thickness and width will decrease.

Note:
Solids generally have a definite and constant volume until and unless a significant amount of energy (usually in the form of heat) is acted upon it, thus causing a subsequent change in its physical state.