NCERT Solutions for class 11 Physics Chapter 9: Mechanical properties of solids

NCERT Solutions for Class 11 Physics Chapter 9: Mechanical Properties of Solids are provided in this article below. Mechanical properties of solids define the various characteristics of solids such as their resistance to deformation and their strength.

Chapter 9 Mechanical Properties of Solids belongs to Unit 7 Properties of Bulk Matter. Unit 7 along with Unit 8 Thermodynamics and Unit 9 Behaviour of Perfect Gases and Kinetic Theory of Gases has a weightage of 20 marks in the Class 11 Examination. The Class 11 NCERT Solutions for Mechanical Properties of Solids discusses concepts such as Elastic behaviour of solids, Hooke’s law, and the Stress-strain curve.

Download PDF: NCERT Solutions for Class 11 Physics Chapter 9

NCERT Solutions for Class 11 Physics Chapter 9

Class 11 Physics Chapter 9 – Concepts Covered

Stress is the ratio of the internal force F, produced when a substance is deformed, to the area A over which the force acts.

$Stress = {F \over A}$

Strain is the ratio of the change in shape or size to the original shape or size. It is just a number and has no dimensions.

Strain is of 3 types – Longitudinal strain, Volumetric strain, and Shear strain

As per Hooke’s law, the ratio of stress to the corresponding strain produced within elastic limits is a constant. This constant is known as the modulus of elasticity.

$F_s = -kx$

For a solid, in wire or a thin rod form, Young’s modulus of elasticity is defined as the ratio of longitudinal stress to longitudinal strain within the elastic limit.

Young's Modulus

Poisson’s Ratio – The ratio of change in diameter (ΔD) to the original diameter (D) is known as lateral strain. The ratio of change in length (Δl) to the original length (l) is known as longitudinal strain. The ratio of lateral strain to the longitudinal strain is called Poisson’s ratio.

$Poisson's\ Ratio\ = {Lateral\ strain \over Longitudinal\ Strain}$

Class 11 Physics Chapter 9 Related Guides –

Stress and Strain	Elastic Moduli	Shear Modulus
Bulk Modulus	Shearing Stress	Yield Strength
Elastic Limit	Tensile Stress	Elastomers
Beam Deflection Formula	Solid Deformation	Stress Formula

Class 11 Physics Study Guides:

Difference between in Physics	Physics Formula	Class 11 Physics Notes
Relation between articles in Physics	Derivations in Physics	Physics Study Notes
NCERT Solutions for Class 11 Physics	Physics Constants	SI Units in Physics

CBSE CLASS XII Related Questions

1.
Write two advantages of reflecting telescope over refracting telescope.
View Solution
2.
Read the following paragraph and answer the questions that follow.
A p-type or n-type semiconductor can be converted into a p-n junction by doping it with suitable impurity. The motion of majority charge carriers causes diffusion current across the junction while the barrier electric field causes motion of minority carriers for drift current. In case of unbiased diode, the diffusion and drift currents are equal. This equilibrium is disturbed by the biasing batteries. Diodes, therefore, allow currents in one direction. This property of diode is used in making rectifiers.
3.
A student sets up the circuit as shown in the figure to find the value of unknown resistance X and records a set of readings of the voltmeter and the ammeter by using the rheostat.
4.
An electric field $\vec{E}$ is established across the ends of a cylindrical conductor of length L and area of cross-section A. Discuss how electrons attain an average velocity, independent of time. Hence, obtain a relation between current in the conductor and this ‘average velocity’ of electrons.
View Solution
5.
Consider the nuclear reaction $ X \to Y + Z $. Let $ M_x $, $ M_y $, and $ M_z $ be the masses of the three nuclei X, Y, and Z respectively. Then which of the following relations hold true?
- $ (M_x - M_z)<M_y $
- $ (M_x - M_y)<M_z $
- $ M_x>(M_y + M_z) $
- $ M_x<(M_y + M_z) $
View Solution
6.
Capacitors are manufactured with certain standard capacitances and working voltages. However, these standard values may not be the ones that are actually needed in a particular application. Two or more capacitors can be grouped in series or in parallel to achieve desired capacitance and voltage. When connected in series, the total capacitance decreases while the voltage rating increases, whereas in parallel connections, the total capacitance increases and maintains the same voltage rating. A capacitor stores energy in the electric field between its plates and stored energy is proportional to the square of the voltage and capacitance $U = \frac{1}{2}CV^2$, where symbols have their usual meanings.
Two capacitors, one of $3 \ \mu$F and the other of $6 \ \mu$F, are connected in series in the circuit as shown in the figure, for a long time. }