# 11 - Elasticity Questions Answers Sir pls tell whether the stress is compressive or tensile and the value of stress
Joshi sir comment

Due to inner sphere attraction, outer sphere contracts so it is compressive stress.

Physics >> Mechanics Part 2 >> Elasticity Medical Exam

A solid sphere is subjected to uniform pressure from all direction. The ratio of volumetric strain to lateral strain produced in it, is

Joshi sir comment

V = 4/3 πr3

so dV = 4πr2

now calculate dV/V

Physics >> Mechanics Part 2 >> Elasticity Medical Exam

What is the length of a wire whose density is 8 g/cm3, which suspended vertically, would break due to its own weight? [Breaking stress of wire is 2.4 x 108 N/m2]

Joshi sir comment

use stress = force/area

Physics >> Mechanics Part 2 >> Elasticity Medical Exam

When a load of 8 kg is hung on a wire, then extension of 3 cm takes place, the work done by internal forces of wire is

Joshi sir comment
Calculate work done by weight of body hung
Physics >> Mechanics Part 2 >> Elasticity Medical Exam

The work done per unit volume to stretch the length of area of cross-section 2 mm2 by 2% will be [ Y = 8 x 1010 N/m2 ]

Joshi sir comment
W =1/2 Y (dl/l)2 V V represents volume Now solve
Physics >> Mechanics Part 2 >> Elasticity Medical Exam

To break a wire a stress of 9 x 105 N/m2 is required. If density of the material of wire is 3 g/cc, then the minimum length of wire which will break by its own weight will be

Joshi sir comment

use stress = force /area

Physics >> Mechanics Part 2 >> Elasticity Medical Exam

A steel wire is 1m long and 1mm2 in area of cross-section. If it takes 200 N to stretch this wire by 1mm, how much force will be required to stretch a wire of the same material as well as diameter from its normal length of 10m to a length of 1002 cm?

Joshi sir comment

by first set of data calculate Y then by using this Y solve the question

Physics >> Mechanics Part 2 >> Elasticity Medical Exam

The length of wire, when M1 is hung from it, is l1 and is l2 with both M1 and M2 hanging. The natural length of wire is [ M2 is on M1 ]

Joshi sir comment

Y = M1gL/A(l1-L) = (M1+M2)gL/(l2-L)

solve for L

Physics >> Mechanics Part 2 >> Elasticity Medical Exam

A nylon rope 3 cm in diameter has a breaking strength of 1.5 x 105 N. The breaking strength for a similar rope 1.5cm in diameter is