CBSE Class 11 Physics – MCQ and Online Tests – Unit 9 – Mechanical Properties of Solids
Every year CBSE schools conducts Annual Assessment exams for 6,7,8,9,11th standards. These exams are very competitive to all the students. So our website provides online tests for all the 6,7,8,9,11th standard’s subjects. These tests are also very effective and useful for those who preparing for any competitive exams like Olympiad etc. It can boost their preparation level and confidence level by attempting these chapter wise online tests.
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CBSE Class 11 Physics – MCQ and Online Tests – Unit 9 – Mechanical Properties of Solids
Question 1.
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
Answer: (c) There is an attractive force between the molecules
Question 2.
A body of mass 1 kg is attached to one end of a wire and rotated in horizontal circle of diameter 40 cm with a constant speed of 2 m/s. what is the area of cross-section of the wire if the stress developed in the wire is 5 × 106 N/m²?
(a) 2 mm²
(b) 3 mm²
(c) 4 mm²
(d) 5 mm²
Answer
Answer: (c) 4 mm²
Question 3.
Two wires A and B are of the same length. The diameters are in the ratio 1 : 2 and the Youngs modulus are in ratio 2 : 1. if they are pulled by the same force, then their elongations will be in ratio
(a) 4 : 1
(b) 1 : 4
(c) 1 : 2
(d) 2 : 1
Answer
Answer: (d) 2 : 1
Question 4.
Hookes law essentially defines
(a) Stress
(b) Strain
(c) Yield point
(d) Elastic limit
Answer
Answer: (d) Elastic limit
Question 5.
Longitudinal strain is possible in the case of
(a) Gases
(b) Liquid
(c) Only solids
(d) Only gases & liquids
Answer
Answer: (c) Only solids
Question 6.
Two wires have the same material and length, but their masses are in the ration of 4 : 3. If they are stretched by the same force, their elongations will be in the ratio of
(a) 2 : 3
(b) 3 : 4
(c) 4 : 3
(d) 9 : 16
Answer
Answer: (b) 3 : 4
Question 7.
A rubber cord of cross sectional area 1 mm² and unstretched length 10 cm is stretched to 12 cm and then released to project a stone of mass 5 gram. If Y for rubber = 5 ? 108N/m², then the tension in the rubber cord is
(a) 25 N
(b) 50 N
(c) 100 N
(d) 200 N
Answer
Answer: (c) 100 N
Question 8.
Out of the following materials, whose elasticity is independent of temperature?
(a) Copper
(b) Invar steel
(c) Brass
(d) Silver
Answer
Answer: (b) Invar steel
Question 9.
An iron bar of length l m and cross section A m² is pulled by a force of F Newton from both ends so as to produce and elongation in meters. Which of the following statement statements is correct
(a) Elongation is inversely proportional to length l
(b) Elongation is directly proportional to cross section A
(c) Elongation is inversely proportional to A
(d) Elongation is directly proportional to Youngs modulus
Answer
Answer: (c) Elongation is inversely proportional to A
Question 10.
The ratio of the change in dimension at right angles to the applied force to the initial dimension is known as
(a) Youngs modulus
(b) Poissons ratio
(c) Lateral strain
(d) Shearing strain
Answer
Answer: (c) Lateral strain
Question 11.
A body of mass 1 kg is attached to one end of a wire and rotated in horizontal circle of diameter 40 cm with a constant speed of 2 m/s. what is the area of cross-section of the wire if the stress developed in the wire is 5 × 106 N/m²?
(a) 2 mm²
(b) 3 mm²
(c) 4 mm²
(d) 5 mm²
Answer
Answer: (c) 4 mm²
Question 12.
In a wire, when elongation is 2 cm energy stored is E. if it is stretched by 10 cm, then the energy stored will be
(a) E
(b) 2 E
(c) 4 E
(d) 25 E
Answer
Answer: (d) 25 E
Question 13.
A rubber cord of cross sectional area 1 mm² and unstretched length 10 cm is stretched to 12 cm and then released to project a stone of mass 5 gram. If Y for rubber = 5 ? 108N/m², then the tension in the rubber cord is
(a) 25 N
(b) 50 N
(c) 100 N
(d) 200 N
Answer
Answer: (c) 100 N
Question 14.
In a wire, when elongation is 2 cm energy stored is E. if it is stretched by 10 cm, then the energy stored will be
(a) E
(b) 2 E
(c) 4 E
(d) 25 E
Answer
Answer: (d) 25 E
Question 15.
One end of a steel wire of area of cross-section 3 mm² is attached to the ceiling of an elevator moving up with an acceleration of 2.2 m/s². if a load of 8 kg is attached at its free end, then the stress developed in the wire will be
(a) 8 × 106 N/m²
(b) 16 × 106 N/m²
(c) 20 × 106 N/m²
(d) 32 × 106 N/m²
Answer
Answer: (d) 32 × 106 N/m²
Question 16.
The ratio of the change in dimension at right angles to the applied force to the initial dimension is known as
(a) Youngs modulus
(b) Poissons ratio
(c) Lateral strain
(d) Shearing strain
Answer
Answer: (c) Lateral strain
Question 17.
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/oC and Y = 1011 N/m²)
(a) 103 N
(b) 104 N
(c) 105
(d) 109 N
Answer
Answer: (b) 104 N
Question 18.
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
(a) 0.09°
(b) 0.9°
(c) 9°
(d) 90°
Answer
Answer: (a) 0.09°
Question 19.
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
(a) 2 : 1
(b) 4 : 1
(c) 1 : 4
(d) 1 : 2
Answer
Answer: (c) 1 : 4
Question 20.
Four wires whose lengths and diameter respectively are given below are made of the same material. Which of these will have the largest extension when same tension is applied?
(a) 0.50 m, 0.50 mm
(b) 1.00 mm, 1.00 mm
(c) 2.00 m, 2.00 mm
(d) 4.00 m, 4.00 mm
Answer
Answer: (a) 0.50 m, 0.50 mm
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