### NEET Physics - New - Mechanical Properties of Solids

#### Question - 1

A wire of length L, area of cross section A is hanging from a fixed support. The length of the wire changes to L1 when mass M is suspended from its free end. The expression for Young's modulus is___

• A $\frac{m g L}{A\left(L_{1}-L\right)}$
• B $\frac{m g L_{1}}{A L}$
• C $\frac{M g\left(L_{1}-L\right)}{A L}$
• D $\frac{M g L}{A L_{1}}$

#### Question - 2

A copper rod of 88 cm and an aluminium rod of unknown length have their increase in length independent of increase in temperature. The length of aluminium rod is: $\left(\mathrm{a}_{\mathrm{Cu}}=1.7 \times 10^{-5} \mathrm{~K}^{-1}\right.$ and $\left.\mathrm{a}_{\mathrm{Al}}^{-2.2} \times 10^{-5} \mathrm{~K}^{-1}\right)$____

• A $113.9 \mathrm{~cm}$
• B $88 \mathrm{~cm}$
• C $68 \mathrm{~cm}$
• D $6.8 \mathrm{~cm}$

#### Question - 3

When a block of mass M is suspended by a long wire of length L, the length of the wire becomes L + I. The elastic potential energy stored in the extended wire is____

• A $\mathrm{mg} \mathrm{I}$
• B $\frac{1}{2} \mathrm{mgl}$
• C $\frac{1}{2} \mathrm{mgL}$
• D $\mathrm{mgl}$

#### Question - 4

The approximate depth of an ocean is 2700 m. The compressibility of water is $45.4 \times 10^{-11} \mathrm{~Pa}^{-1}$ and density of water is $10^{3} \mathrm{~kg} / \mathrm{m}^{3}$. What fractional compression of water will be obtained at the bottom of the ocean?

• A $1.0 \times 10^{-2}$
• B $1.2 \times 10^{-2}$
• C $1.4 \times 10^{-2}$
• D $0.8 \times 10^{-2}$

#### Question - 5

Copper of fixed volume V is drawn into wire of length $l$ . When this wire is subjected to a constant force F. The extension produced in the wire is Which $\Delta l$. of the following graph is a straight line?

• A $\Delta l$ versus 1/l
• B $\Delta l$versus l2
• C $\Delta l$ versus 1/l2
• D $\Delta l$ versus l

#### Question - 6

If the ratio of diameters, lengths and Young's modulus of steel and copper wires shown in the figure are p, q and s respectively, then the corresponding ratio of increase in their lengths would be______

• A $\frac{7 q}{(5 s p)}$
• B $\frac{5 q}{\left(7 s p^{2}\right)}$
• C $\frac{7 q}{\left(5 s p^{2}\right)}$
• D $\frac{2 q}{(5 s p)}$

#### Question - 7

The following four wires are made of the same material. Which of these will have the largest extension when the same tension is applied?

• A $Length =100 \mathrm{~cm}, diameter =1 \mathrm{~mm}$
• B $Length =200 \mathrm{~cm}, diameter =2 \mathrm{~mm}$
• C $Length =300 \mathrm{~cm}, diameter =3 \mathrm{~mm}$
• D $Length =50 \mathrm{~cm}, diameter =0.5 \mathrm{~mm}$

#### Question - 8

The compressibility of water is $4 \times 10^{-5}$ per unit atmospheric pressure. The decrease in volume of $100 \mathrm{~cm}^{3}$ of water under a pressure of 100 atmosphere will be___

• A $0.4 \mathrm{~cm}^{3}$
• B $1 \times 10^{-5} \mathrm{~cm}^{3}$
• C $0.025 \mathrm{~cm}^{3}$
• D $0.004 \mathrm{~cm}^{3}$

#### Question - 9

When an elastic material with Young's modulus Y is subjected to stretching stress S, elastic energy stored per unit volume of the material is_____

• A $YS/2$
• B $\mathrm{S}^{2} \mathrm{Y} / 2$
• C $\mathrm{S}^{2} / 2 \mathrm{Y}$
• D $\mathrm{S} / 2 \mathrm{Y}$

#### Question - 10

Two wires A and B are of the same material. Their lengths are in the ratio 1: 2 and the diameter are in the ratio 2: 1. If they are pulled by the same force, then increase in length will be in the ratio____

• A 2: 1
• B 1: 4
• C 1: 8
• D 8: 1