JEE Physics Mechanical Properties Of Solids MCQs Set A

Question. Due to addition of impurities, the modulus of elasticity
(a) May increase or decrease
(b) Increases
(c) Decreases
(d) Remains constant

Answer: A

Question. The shear strain is possible in
(a) Solids
(b) Liquids
(c) Gases
(d) All of these

Answer: A

Question. The ratio of radii of two wires of same material is 2 : 1. If these wires are stretched by equal force, the ratio of stresses produced in them is
(a) 1 : 4
(b) 1 : 2
(c) 4 : 1
(d) 2 : 1

Answer: A

Question. A load of 2 kg produces an extension of 1 mm in a wire of 3 m in length and 1 mm in diameter. The Young’s modulus of wire will be
(a) 7.48 × 10¹⁰ Nm^–2
(b) 3.25 × 10¹⁰ Nm^–2
(c) 7.48 × 10¹² Nm²
(d) 7.48 × 10^–10 Nm^–2

Answer: A

Question. Young’s modulus depends upon
(a) Temperature of material
(b) Stress applied on material
(c) Strain produced in material
(d) All of these

Answer: A

Question. The value of Young’s modulus for a perfectly rigid body is
(a) Infinite
(b) Zero
(c) Less than 1
(d) 1

Answer: A

Question. The breaking stress of aluminium is 7.5 × 10⁷ Nm^–2. The greatest length of aluminium wire that can hang vertically without breaking is (Density of aluminium is 2.7 × 10³ kg m^–3)
(a) 2.83 × 10³ m
(b) 0.283 × 10³ m
(c) 28.3 × 10³ m
(d) 283 × 10³ m

Answer: A

Question. A steel wire of diameter 2 mm has a breaking strength of 4 × 10⁵ N. What is the breaking force of similar steel wire of diameter 1.5 mm?
(a) 2.3 × 10⁵ N
(b) 2.6 × 10⁵ N
(c) 3 × 10⁵ N
(d) 1.5 × 105 N

Answer: A

Question. A steel wire is 1 m long and 1 mm² in area of cross-section. If it takes 200 N to stretch this wire by 1 mm, how much force will be required to stretch a wire of the same material as well as diameter from its normal length of 10 m to a length of 1002 cm?
(a) 400 N
(b) 2000 N
(c) 200 N
(d) 1000 N

Answer: A

Question. A wire 2 m in length suspended vertically stretches by 10 mm when mass of 10 kg is attached to the lower end. The elastic potential energy gain by the wire is (take g = 10 m/s²)
(a) 0.5 J
(b) 5 J
(c) 50 J
(d) 500 J

Answer: A

Question. A spherical ball contracts in volume by 0.01% when subjected to a normal uniform pressure of 100 atm. The Bulk modulus of its material is
(a) 1.01 × 10¹¹ Nm^–2
(b) 1.01 × 10¹² Nm^–2
(c) 1.01 × 10¹⁰ Nm^–2
(d) 1.0 × 10¹³ Nm^–2

Answer: A

Question. What is the percentage increase in length of a wire of diameter 2.5 mm, stretched by a force of 100 kg wt? Young’s modulus of elasticity of wire = 12.5 × 10¹¹ dyne/cm²
(a) 0.16%
(b) 0.32%
(c) 0.08%
(d) 0.12%

Answer: A

Question. A steel rod has a radius 10 mm and a length of 1.0 m. A force stretches it along its length and produces a strain of 0.32%. Young’s modulus of the steel is 2.0 × 10¹¹ Nm^–2. What is the magnitude of the force stretching the rod?
(a) 201 kN
(b) 100.5 kN
(c) 78 kN
(d) 150 kN

Answer: A

Question. The proportional limit of steel is 8 × 10⁸ N/m² and its Young’s modulus is 2 × 10¹¹ N/m². The maximum elongation, a one metre long steel wire can be given without exceeding the elastic limit is
(a) 4 mm
(b) 2 mm
(c) 1 mm
(d) 8 mm

Answer: A

Question. In a series combination of copper and steel wires of same length and same diameter, a force is applied at one of their ends while the other end is kept fixed. The combined length is increased by 2 cm. The wires will have
(a) Same stress and different strain
(b) Different stress and different strain
(c) Same stress and same strain
(d) Different stress and same strain

Answer: A

Question. Select the correct alternative(s)
(a) Elastic forces are not always conservative
(b) Elastic forces are always conservative
(c) Elastic forces are conservative only when Hooke’s law is obeyed
(d) Elastic forces are not conservative

Answer: A

Question. The Poisson’s ratio of a material is 0.5. If a force is applied to a wire of this material, there is a decrease in the cross-sectional area by 4%. The percentage increase in the length is
(a) 4%
(b) 2.5%
(c) 2%
(d) 1%

Answer: A

Question. If the Bulk modulus of lead is 8.0 × 10⁹ N/m² and the initial density of the lead is 11.4 g/cc, then under the pressure of 2.0 × 10⁸ N/m², the density of the lead is
(a) 11.7 g/cc
(b) 11.6 g/cc
(c) 11.5 g/cc
(d) 11.3 g/cc

Answer: A

Question. Two wires A and B of same material have radii in the ratio 2 : 1 and lengths in the ratio 4 : 1. The ratio of the normal forces required to produce the same change in the lengths of these two wires is
(a) 1 : 1
(b) 2 : 1
(c) 1 : 2
(d) 1 : 4

Answer: A

Question. For a given material, the Young’s modulus is 2.4 times its modulus of rigidity. Its Poisson’s ratio is
(a) 0.2
(b) 0.4
(c) 1.2
(d) 2.4

Answer: A

Question. When the temperature of a gas is 20°C and pressure is changed from P₁ = 1.01 × 10⁵ Pa to P₂= 1.165 × 10₅ Pa, then the volume changes by 10%. The Bulk modulus is
(a) 1.55 × 10⁵ Pa
(b) 1.01 × 10⁵ Pa
(c) 1.4 × 10⁵ Pa
(d) 0.115 × 10⁵ Pa

Answer: A

Question. Hooke’s law is applicable for
(a) Elastic materials only
(b) Elastomers only
(c) Plastic materials only
(d) All of these

Answer: A

Question. A wire suspended vertically from one end is stretched by attaching a weight 200 N to the lower end. The weight stretches the wire by 1 mm. The elastic potential energy gained by the wire is
(a) 0.1 J
(b) 0.2 J
(c) 0.4 J
(d) 10 J

Answer: A

Question. Work done by restoring force in a string within elastic limit is –10 J. Maximum amount of heat produced in the string is
(a) 10 J
(b) 20 J
(c) 5 J
(d) 15 J

Answer: A

Question. Which of the following affects the elasticity of a substance?
(a) All of these
(b) Impurity in substance
(c) Change in temperature
(d) Hammering

Answer: A

Question. Select the wrong definition
(a) Plastic body – which can be easily melted
(b) Elastic limit – beyond which property of elasticity vanishes
(c) Elasticity – property of regaining original configuration
(d) Deforming Force – force that changes configuration of body

Answer: A

Question. The ratio of adiabatic to isothermal elasticity of a diatomic gas is
(a) 1.4
(b) 1.67
(c) 1.33
(d) 1.27

Answer: A

Question. A uniform cubical block is subjected to volumetric compression, which decreases its each side by 2%. The Bulk strain produced in it is
(a) 0.06
(b) 0.12
(c) 0.02
(d) 0.03

Answer: A

Question. A spherical ball contracts in volume by 0.02%, when subjected to a normal uniform pressure of 50 atmosphere. The Bulk modulus of its material is
(a) 2.5 × 10¹⁰ N/m²
(b) 1 × 10¹³ N/m²
(c) 2 × 10¹⁰ N/m²
(d) 1 × 10¹¹ N/m²

Answer: A

Question. The Poisson's ratio cannot have a value of
(a) 0.7
(b) 0.2
(c) 0.1
(d) 0.5

Answer: A

Question. A material has Poisson’s ratio 0.5. If a uniform rod of it suffers a longitudinal strain of 3 × 10^–3, what will be percentage increase in volume?
(a) 0%
(b) 5%
(c) 3%
(d) 2%

Answer: A

Question. The substances having very short plastic region are
(a) Brittle
(b) Ductile
(c) Malleable
(d) All of these

Answer: A

Question. Correct pair is
(a) Reciprocal of Bulk modulus – ComChange in shape – Longitudinal strainpressibility
(b) None of these
(c) Change in volume – Shear strain
(d) Change in length – Bulk strain

Answer: A