Elasticity Questions: Paper 03

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1.	The magnitude of the force developed by raising the temperature from 0 °C to 100 °C of the iron bar of 1.00 m long and 1 cm² cross-section when it is held so that it is not permitted to expand or bend is (a = 10^-⁵/°C and Y = 10¹¹ N/m²) (CPMT 91) (a) 10³ N (b) 10⁴ N (c) 10⁵ (d) 10⁹ N Answer: (b)
2.	Theoretical value of Poisson’s ratio lies between (AIIMS 85) (a) - 1 to 0.5 (b) -1 to -2 (c) 0.5 to 1 (d) None Answer: (a)
3.	One end of a uniform wire of length L and of weight W is attached rigidly to a point on the roof and a weight W₁ is suspended from its lower end. If S is the area of cross-section of the wire, the stress in the wire at a height from its lower end is, (IIT 92) (a) (b) (c) (d) Answer: (c)
4.	There is no change in the volume of a wire due to change in its length on stretching. The poison’s ration of the material of the wire is (MHT-CET 2004) (a) + .50 (b) - 0.50 (c) 0.25 (d) - 0.25 Answer: (b)
5.	A stretched wire has a Young’s modulus Y and energy density E. the strain in the stretched wire is (a) (b) (c) (d) Answer: (a)
6.	Strain has (a) No units but only dimensions (b) Only units but no dimensions (c) No units, no dimensions but a constant value (d) No units, no dimensions but a variable value Answer: (d)
7.	A stretching wire has a Young’s modulus Y and energy density E. the strain in a stretching wire is (MHT-CET-2006) (a) (b) (c) (d) Answer: (d)
8.	The change in the shape of a regular boy is due to (Andhra medical 80) (a) Bulk strain (b) Shearing strain (c) Longitudinal strain (d) Volume strain Answer: (b)
9.	When impurities are added to an elastic substance, its elasticity (a) Increases (b) Decreases (c) Becomes zero (d) May increase or decrease Answer: (d)
10.	To compress a liquid by 10% of its original volume, the pressure required is 2 ´ 10⁵ atmosphere. The bulk modulus of liquid is (MHT-CET-2004) (a) 2 ´ 105 N/m² (b) 2 ´ 107 N/m² (c) 2 ´ 104 N/m² (d) 2 ´ 106 N/m² Answer: (d)
11.	The upper end of wire 1 m long and 2 mm radius is clamped. The lower end is twisted through an angle of 45°. The angle of shear is (NCERT 90 PMT MP 90, 96) (a) 0.09° (b) 0.9° (c) 9° (d) 90° Answer: (a)
12.	Longitudinal strain is possible in the case of (a) Gases (b) Liquid (c) Only solids (d) Only gases & liquids Answer: (c)
13.	Which of the following is correct statement from the given graph plotted, for four wires of same material and same thickness (MHT-CET-2001) (a) A has largest length (b) D has largest length (c) C has largest length (d) B has largest length Answer: (a)
14.	Relation between y, n, k is (MHT-CET-2008) (a) (b) (c) (d) Answer: (c)
15.	When the intermolecular distance increases due to tensile force, then (a) There is no force between the molecules (b) There is a repulsive force between the molecules (c) There is an attractive force between the molecules (d) There is zero resultant force between the molecules Answer: (c)
16.	If a material is heated and annealed, then its elasticity is (a) Increased (b) Decreased (c) Not change (d) Becomes zero Answer: (b)
17.	A long string is stretched by 2 cm and the potential energy is V. if the spring is stretched by 10 cm. its potential energy will be (CPMT 76) (a) (b) (c) 5V (d) 25V Answer: (d)
18.	The radii of two wires of a same material are in ratio 2:1. if the wires are stretched by equal forces, the stress produced in them will be (MHT CET 2005) (a) 2:1 (b) 4:1 (c) 1:4 (d) 1:2 Answer: (c)
19.	The bulk modulus of elasticity of the material of a metal sphere is 2 × 10¹¹ N/m². in open air, atmospheric pressure of 10⁵ N/m² acts on it. What is the fractional decrease in its volume if it kept in a vacuum chamber? (a) 2 × 10^-⁷ (b) 3 × 10^-⁷ (c) 4 × 10^-⁷ (d) 5 × 10^-⁷ Answer: (d)
20.	The Poisson’s ratio of the material of a wire is 0.25. if it is stretched by a force F, the longitudinal strain produced in the wire is 5 × 10^-⁴. What is the percentage increase in its volume? (a) 0.2 (b) 2 × 10² (c) Zero (d) 1.25 × 10^-⁶ Answer: (c)
21.	The bulk modulus of a gas is 6 ´ 10³ N/m². the additional pressure needed to reduce the volume of the liquid by 10% is (MHT-CET-2007) (a) 1200 N/m² (b) 600 N/m² (c) 2400 N/m² (d) 1600 N/m² Answer: (b)
22.	Hooke’s law essentially defines (PMTMP 88) (a) Stress (b) Strain (c) Yield point (d) Elastic limit Answer: (d)
23.	Strain energy per unit volume is given by (MHT-CET 2003) (a) (b) (c) (d) None of these Answer: (a)
24.	The Young’s modulus for a plastic body is (a) One (b) Zero (c) Infinity (d) Less then one Answer: (b)
25.	Four steel wires of the following dimensions are stretched with the same force. Which one of them will have the largest extension? (a) L₁ = 50 cm, r₁ = 0.5 mm (b) L₂ = 100 cm, r₂ = 1 mm (c) L₃ = 200 cm, r₃ = 2 mm (d) L₄ = 300 cm, r₄ = 3 mm Answer: (a)