NCERT Solutions for Class 11 Physics Physics Part Ii Chapter 9 Mechanical Properties Of Solids

State hooke’s law?

Define modulas of elasticity and write down its Unit and Dimensions.

Write down the relation beween three types of moduli and poissons ration?

One kg of a diatomic gas is at a pressure of 8 × 10⁴ N/m² . The density of the gas is 4 kg/m^-3. What is the energy of the gas due to its thermal motion?

• 3 × 10⁴ J

• 5× 10⁴ J

• 6× 10⁴ J

• 7× 10⁴ J

Two wires are made of the same material and have the same volume. However wire 1 has cross-section area A and wire 2 has cross–sectional area 3A. If the length of wire 1 increases by ∆x on applying force F, how much force is needed to stretch wire 2 by the same amount?

• F

• 4F

• 9F

• 6F

A transparent solid cylindrical rod has a refractive index of 2√3. It is surrounded by air. A light ray is incident at the midpoint of one end of the rod as shown in the figure.θ The incident angle θ for which the light ray grazes along the wall of the rod is 

If S is stress and Y is Young’s modulus of material of a wire, the energy stored in the wire per unit volume is

• 2S²Y

• S²/2Y

• 2Y/S²

• S/2Y

One solid sphere A and another hollow sphere B are of same mass and same outer radii. Their moment of inertia about their diameters are respectively I_A and I_B such that


Where d_A and d_B are their densities.

• I_A = I_B

• I_A > I_B

• I_A < I_B

• I_A/I_B = d_A/d_B

What would be the work done in stretching a wire.

A granite rod of 60 cm length is clamped at its middle point and is set into longitudinal vibrations. The density of granite is 2.7 x 10³ kg/m³ and its Young’s modulus is 9.27 x 10¹⁰ Pa. What will be the fundamental frequency of the longitudinal vibrations?

• 7.5 kHz

• 5 kHz

• 2.5 kHz

• 10 kHz