properties of matter

Question 1

elastic behaviour

Answer 1

Elasticity is the property of body by virtue of which a body regains or tends to regain its
original configuration (shape as well as size), when the external deforming forces acting
on it, is removed.

Question 2

stress

Answer 2

The internal restoring force per unit area of cross-section of the deformed body is called
stress.
σ=restoring stress/area=F/A
SI unit of stress is Nm−2
or pascal (Pa)

Question 3

normal or longitudinal stress

Answer 3

If area of cross-section of a rod is A and a deforming force F is applied along the length of
the rod and perpendicular to its cross-section, then stress produced in the rod is called
normal or longitudinal stress.
Longitudinal stress =Fn/A

Question 4

longitutnal stress is of two types

Answer 4

(i) Tensile stress When length of the rod is INCREASED on application of deforming force over it, then stress
produced in rod is called tensile stress.
(ii) Compressive stress When length of the rod is DECREASED on application of deforming force, then the stress produced is called compressive stress.

Question 5

volumetric stress

Answer 5

When a force is applied on a body such that it produces a change in volume and density, shape remaining same
(i) at any point, the force is perpendicular to its surface.
(ii) at any small area, the magnitude of force is directly
proportional to its area. Then, force per unit area is called volumetric stress.
∴ Volumetric stress= Fv/A

Question 6

shearing stress or tangential stress

Answer 6

When the force is applied tangentially to a surface, then it is called tangential or shearing stress.
Tangential stress =Ft/A
It produces a change in shape, volume remaining same

Question 7

strain

Answer 7

Strain is the ratio of change in configuration to the original
configuration of the body.
Being the ratio of two similar quantities, strain is a unitless
and dimensionless quantity