Mechanical Properties of Solids PYQs Set 1 (PDF)

Set 1 of 5 · Questions 1-30 of 125

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Mere Teacher · Previous Year Questions NEET Physics · Mechanical Properties of Solids · Set 1 (Q1-30)
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1. $Young's modulus of a perfect rigid body is$ (1) $infinity$ (2) $between zero and unity$ (3) $zero$ (4) $unity.$ 2. $A wire of length L and radius r is clamped at one end. If its other end is pulled by a force F, its length increases by l . If the radius of the wire and the applied force both are reduced to half of their original values keeping original length constant, the increase in length will become.$ (1) $3 times$ (2) $3/2 times$ (3) $4 times$ (4) $2 times$ 3. $In a photoelectric experiment, increasing the intensity of incident light:$ (1) $increases the number of photons incident and also increases the K.E. of the ejected electrons$ (2) $increases the frequency of photons incident and increases the K.E. of the ejected electrons.$ (3) $increases the frequency of photons incident and the K.E. of the ejected electrons remains unchanged$ (4) $increases the number of photons incident and the K.E. of the ejected electrons remains unchanged$ 4. $An electron having de-Broglie wavelength λ is incident on a target in a X-ray tube. Cut-off wavelength of emitted X-ray is:$ (1) $0$ (2) $\frac{2 m ^{2} c ^{2} λ ^{2}}{h ^{2}}$ (3) $\frac{2 mc λ ^{2}}{h}$ (4) $\frac{hc}{mc}$ 5. $A solid copper cube of 7 cm edge is subjected to a hydraulic pressure of 8000 kPa . The volume contraction of the copper cube is (Bulk modulus of copper = 140 GPa)$ (1) $196 \times 10^{- 3} cm^{3}$ (2) $19.6 \times 10^{- 6} cm^{3}$ (3) $19.6 \times 10^{- 3} cm^{3}$ (4) $196 \times 10^{3} cm^{3}$ 6. $The de-Broglie wavelength of a particle having kinetic energy E is λ . How much extra energy must be given to this particle so that the de-Broglie wavelength reduces to 75% of the initial value?$ (1) $\frac{1}{9} E$ (2) $\frac{7}{9} E$ (3) $E$ (4) $\frac{16}{9} E$ 7. $With rise in temperature, the Young's modulus of elasticity$ (1) $changes erratically$ (2) $decreases$ (3) $increases$ (4) $remains unchanged$ 8. $A wire of length 40 cm is stretched by 0.1 cm . The strain on the wire is$ (1) $25 \times 10^{- 4}$ (2) $40 \times 10^{- 4}$ (3) $10 \times 10^{- 4}$ (4) $12.5 \times 10^{- 4}$ 9. $The approximate depth of an ocean is 2700 m. The compressibility of water is 45.4 x and density of water is kg/. What fractional compression of water will be obtained at the bottom of the ocean$ (1) $1.0 x 1 0^{-2}$ (2) $1.2 x 1 0^{-2}$ (3) $1.4 x 1 0^{-2}$ (4) $0.8 x 1 0^{-2}$ 10. $Two wires A and B are made of same material having ratio of lengths \frac{L _{A}}{L _{B}} = \frac{1}{3} and their diameters ratio \frac{d _{A}}{d _{B}} = 2 . If both the wires are stretched using same force, what would be the ratio of their respective elongations?$ (1) $1 : 6$ (2) $1 : 12$ (3) $3 : 4$ (4) $1 : 3$ 11. $Two wires of same length having radius of 2 mm and 1.5 mm respectively are loaded with same weights. Extension of the second wire is double than that of the first wire. What is the ratio of the Young's modulus of the first wire to that of the second wire?$ (1) $8/9$ (2) $9/8$ (3) $¾$ (4) $4/3$ 12. $The normal density of a material is ρ and its bulk modulus of elasticity is K . The magnitude of increase indensity of material, when a pressure P is applied uniformly on all sides, will be:$ (1) $\frac{ρK}{P}$ (2) $\frac{K}{ρP}$ (3) $\frac{PK}{ρ}$ (4) $\frac{ρP}{K}$ 13. $The ratio of hydraulic stress to the corresponding strain is known as$ (1) $Bulk modulus$ (2) $Rigidity modulus$ (3) $Compressibility$ (4) $Young's modulus$ 14. $A metal rod of length L, cross-sectional area A, Young's modulus Y and coefficient of linear expansion α is heated to t^{\circ} C . The work that can be performed by the rod when heated is$ (1) $\frac{YAαL t ^{2}}{2}$ (2) $\frac{YA α ^{2} L t ^{2}}{2}$ (3) $\frac{YA α ^{2} L ^{2} t ^{2}}{2}$ (4) $\frac{YAαLt}{2}$ 15. $The area of cross section of the rope used to lift a load by a crane is 2.5 x 1 0^{- 4} m^{2} . The maximum lifting capacity of the crane is 10 metric tons. To increase the lifting capacity of the crane to 25 metric tons, the required area of cross section of the rope should be: (take g= 10 m s^{- 2})$ (1) $6.25 x 1 0^{- 4} m^{2}$ (2) $10 x 1 0^{- 4} m^{2}$ (3) $1 x 1 0^{- 4} m^{2}$ (4) $1.67 x 1 0^{- 4} m$ 16. $The work done in stretching a spring of natural length 25 cm and spring constant 50 Nm^{- 1} from 50 cm to 60 cm is$ (1) $1.5 J$ (2) $2 J$ (3) $3.5 J$ (4) $5 J$ 17. $Young's modules of material of a wire of length ' L' and cross-sectional area A is Y . If the length of the wire is doubled and cross-sectional area is halved then Young's modules will be$ (1) $\frac{Y}{4}$ (2) $4 Y$ (3) $Y$ (4) $2 Y$ 18. $Two wires A and B made of different materials of lengths 6.0 cm and 5.4 cm , respectively and area of cross sections 3.0 \times 10^{- 5} m^{2} and 4.5 \times 10^{- 5} m^{2}, respectively are stretched by the same magnitude under a given load. The ratio of the Young's modulus of A to that of B is x : 3 . The value of x is____.$ (1) $2$ (2) $1$ (3) $4$ (4) $5$ 19. $An electron of mass m_{e} and a proton of mass m_{p} are accelerated through the same potential difference. The ratio of the de-Broglie wavelength associated with the electron to that with the proton is:-$ (1) $\frac{m _{p}}{m _{e}}$ (2) $1$ (3) $\frac{m _{p}}{m _{e}}$ (4) $\frac{m _{e}}{m _{p}}$ 20. $The average depth of Indian ocean is about . The value of fractional compression of water at the bottom of the ocean is (given that the bulk modulus of water is H O )$ (1) $3.4 \times 10^{- 2}$ (2) $1.34 \times 10^{- 2}$ (3) $4.13 \times 10^{- 2}$ (4) $13.4\times 1 0^{- 2}$ 21. $An electron moving with speed v and a photon moving with speed c, have same D-Broglie wavelength. The ratio of kinetic energy of electron to that of photon is:$ (1) $\frac{3 c}{v}$ (2) $\frac{v}{3 c}$ (3) $\frac{v}{2 c}$ (4) $\frac{2 c}{v}$ 22. $The bulk modulus of a spherical object is’B’. If it is subjected to uniform pressure ‘p’, the fractional decrease in radius is:$ (1) $\frac{p}{B}$ (2) $\frac{B}{3 p}$ (3) $\frac{3 p}{B}$ (4) $\frac{p}{3 B}$ 23. $What is the work done in stretching a uniform metal wire of length from 2 m to 2.004 m with an area of cross section 10^{- 6} m^{2} ? [Young's modulus of the wire = 2 \times 10^{11} N / m^{2}]$ (1) $1.6 J$ (2) $0.8 J$ (3) $8 J$ (4) $16 J$ 24. $The pressure that has to be applied to the ends of a steel wire of length 10 cm to keep its length constant when its temperature is raised by 100°C is: (For steel Young's modulus is 2 \times 1 0^{11} N m^{-2} and coefficient of thermal expansion is 1.1 \times 1 0^{-5} K^{-1})$ (1) $2.2 \times 1 0^{8} Pa$ (2) $2.2 \times 1 0^{9} Pa$ (3) $2.2 \times 1 0^{7} Pa$ (4) $2.2 \times 1 0^{6} Pa$ 25. $Choose the correct relationship between Poisson ratio (σ), bulk modulus (K) and modulus of rigidity (η) of a given solid object:$ (1) $σ = \frac{3 K - 2 η}{6 K + 2 η}$ (2) $σ = \frac{6 K + 2 η}{3 K - 2 η}$ (3) $σ = \frac{3 K + 2 η}{6 K + 2 η}$ (4) $σ = \frac{6 K - 2 η}{3 K - 2 η}$ 26. $When a block of mass M is suspended by a long wire of length L, the length of the wire becomes (L + λ). The elastic potential energy stored in the extended wire is:$ (1) $\frac{1}{2} MgL$ (2) $Mgλ$ (3) $MgL$ (4) $\frac{1}{2} Mgλ$ 27. $How much pressure (in atm) is needed to compress a sample of water by 0.4 % ? (Assume, Bulk modulus of water \approx 2.0 \times 10^{9} Pa)$ (1) $60 atm$ (2) $70 atm$ (3) $80 atm$ (4) $90 atm$ 28. $A particle A of mass ’ m ’ and charge ’ q ’ is accelerated by a potential difference of 50 v Another particle B of mass 4 m^{’} and charge ’ q ’ is accelerated by a potential difference of 2500 V . The ratio of de-Broglie wavelength \frac{λ _{A}}{λ _{R}} is$ (1) $10.00$ (2) $0.07$ (3) $14.14$ (4) $4.47$ 29. $A wire of length L, area of cross-section A is hanging from a fixed support. The length of the wire changes to L_{1} when mass M is suspended from its free end. The expression for Young's modulus is [NEET 2020]$ (1) $\frac{Mg ( L _{1} - L )}{AL}$ (2) $\frac{MgL}{A L _{1}}$ (3) $\frac{MgL}{A ( L _{1} - L )}$ (4) $\frac{Mg L _{1}}{AL}$ 30. $A 100 m long wire having cross-sectional area 6.25 x 1 0^{- 4} m^{2} and Young's modulus is 1 0^{10} N m^{- 2} is subjected to a load of 250 N, then the elongation in the wire will be:$ (1) $6.25x 1 0^{- 3} m$ (2) $4x 1 0^{- 4} m$ (3) $6.25 x 1 0^{- 6} m$ (4) $4 x 1 0^{- 3} m$