## Class 11 Physics MCQs Mechanical Properties of Solids for JEE/NEET

Here, you will get Class 11 Physics MCQ of Chapter 9 Mechanical Properties Of Solids for cracking JEE and NEET/AIIMS. By solving these MCQs of Class 11 Physics Chapter 9 Mechanical Properties Of Solids , you will get the confidence to crack JEE or NEET. Practice MCQ Questions for Class 11 Physics with Answers on a daily basis and score well in exams.

## Mechanical Properties Of Solids Class 11 MCQs Questions with Answers

Out of the following materials, whose elasticity is independent of temperature?
(a) Copper
(b) Invar steel
(c) Brass
(d) Silver

A rod of length 10 cm lies along the principal axis of a concave mirror of focal length 10 cm in such a way that its end closer to the pole is 20 cm away from the mirror. The length of the image is
(a) 10 cm
(b) 15 cm
(c) 2.5 cm
(d) 5 cm

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

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

If a glass prism is dipped in water, its dispersive power
(a) increases
(b) decreases
(c) does not change
(d) may increase or decrease depending on whether the angle of the prism is less than or greater than 60º

Consider two cylindrical rods of identical dimensions, one of rubber and the other of steel. Both the rods are fixed rigidly at one end to the roof. A mass M is attached to each of the free ends at the centre of the rods.
(a) both the rods will elongate but there shall be no perceptible change in shape
(b) the steel rod will elongate and change shape but the rubber rod will only elongate
(c) the steel rod will elongate without any perceptible change in shape, but the rubber rod will elongate and the shape of the bottom edge will change to an ellipse
(d) the steel rod will elongate, without any perceptible change in shape, but the rubber rod will elongate with the shape of the bottom edge tapered to a tip at the centre

Answer: (d) the steel rod will elongate, without any perceptible change in shape, but the rubber rod will elongate with the shape of the bottom edge tapered to a tip at the centre

A spring is stretched by applying a load to its free end. The strain produced in the spring is
(a) volumetric
(b) shear
(c) longitudinal and shear
(d) longitudinal

A copper and a steel wire of the same diameter are connected end to end. A deforming force F is applied to this composite wire which causes a total elongation of 1 cm. The two wires will have
(a) the same stress
(b) different stress
(c) the same strain
(d) different strain

Answer: (a) the same stress and (d) different strain

The maximum load a wire can withstand without breaking when its length is reduced to half of its original length, will
(a) be doubled
(b) be half
(c) be four times
(d) remain same

A wire is suspended from the ceiling and stretched under the action of a weight F suspended from its other end. The force exerted by the ceiling on it is equal and opposite to the weight.
(a) tensile stress at any cross-section A of the wire is F/A
(b) tensile stress at any cross-section is zero
(c) tensile stress at any cross-section A of the wire is 2F/A
(d) tension at any cross-section A of the wire is FA

Answer: (a) tensile stress at any cross-section A of the wire is F/A

Hookes law essentially defines
(a) Stress
(b) Strain
(c) Yield point
(d) Elastic limit

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

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: (a) 0.50 m, 0.50 mm

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: (c) Elongation is inversely proportional to A

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 X 108N/m², then the tension in the rubber cord is
(a) 25 N
(b) 50 N
(c) 100 N
(d) 200 N

You are given two wires W1 and W2. Both are made of the same material and are of the same length. The radius of cross-section of W2 is twice that of W1. Same load is suspended from both of them. If the strain in W1 be 4, then calculate the strain in W2.
(a) 8
(b) 4
(c) 2
(d) 1

A steel wire is loaded by 2 kg weight. If the radius of the wire is doubled, then its extension will become
(a) half
(b) four times
(c) one-fourth
(d) double

The energy per unit volume of a strained wire is given by
(a) 1/2 stress × strain
(c) 1/2 extension × stress

Answer: (a) 1/2 stress × strain

In the following data, the four wires made of the same material have length L and radius r. Which 6f these will have the maximum extension when the same force is applied?
(a) L = 50 cm, r = 0.4 mm
(b) L = 100 cm, r = 1 mm
(c) L = 200 cm, r = 2 mm
(d) L = 300 cm, r = 3 mm

Answer: (a) L = 50 cm, r = 0.4 mm

A cable which can support a load W is cut into two equal parts. The maximum load that can be supported by either part is
(a) W
(b) 2W
(c) W/2
(d) W/4

Which of the following affects the elasticity of a substance?
(a) Hammering and annealing
(b) Change in temperature
(c) Impurity in substance
(d) All of the above

Answer: (d) All of the above

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

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°

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 (Temperature Co-efficient = 10-5/oC and Y = 1011 N/m²)
(a) 103 N
(b) 104 N
(c) 105 N
(d) 109 N

Longitudinal strain is possible in the case of
(a) Gases
(b) Liquid
(c) Only solids
(d) Only gases & liquids

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

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) There is an attractive force between the molecules

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 N
(d) 109 N

Which of the following phenomena is used in optical fibres ?
(a) Total internal reflection
(b) Scattering
(c) Diffraction
(d) Refraction

Critical angle of light passing from glass to water is minimum for
(a) red colour
(b) green colour
(c) yellow colour
(d) violet colour

The substance which shows no elastic after effect practically is
(a) steel
(b) rubber
(c) copper
(d) quartz

The breaking stress of a material is defined as
(a) breaking load per unit area
(b) breaking load per unit volume
(c) breaking load per unit length

The maximum length of the steel wire (of density ρ = 7.8 × 10³ kg/m³) which when fixed at one end can hang freely without breaking (breaking stress for steel is 7.8 × 108 Nm-2) is (take g = 10 ms-2):
(a) 1 km
(b) 0.01 km
(c) 0.1 km
(d) 10 km

Girders are made in I shape to
(a) increase its strength
(b) make it appear more elegant
(c) reduce the quantity of material used
(d) none of the above

Answer: (c) reduce the quantity of material used

Two wires A and B are of the same material, but A is half as long and has diameter three times the diameter of wire B. If they are stretched by the same amount, then the required force in wire A must be
(a) three times that on B
(b) one third that on B
(c) nine times that on B
(d) eighteen times that on B

Answer: (d) eighteen times that on B

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: (d) 32 × 106 N/m²

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) There is an attractive force between the molecules

What is the phenomenon of temporary delay in regaining the original configuration by an elastic body, after the removal of a deforming force?
(a) Elastic fatigue
(b) Elasticity
(c) Plasticity
(d) Elastic after effect

In magnitude hydraulic stress is equal to
(a) hydraulic force
(b) hydraulic pressure
(c) restoring force
(d) hydraulic strain

The property of a body by virtue of which it tends to regain its original size and shape when the applied force is removed is called
(a) elasticity
(b) plasticity
(c) rigidity
(d) compressibility

Which of the following statement is False?
(a) The elastomers are the elastic substances which can be subjected to large value of strain i.e. greatly stretched e.g.- rubber
(b) The work done in stretching the wire is stored in it in the form of elastic potential energy
(c) The modulus of rigidity of water is zero
(d) None of these

How does the Young’s modulus vary with the increase of temperature?
(a) increases
(b) decreases
(c) remains constant
(d) first increases and then decreases

For obtaining appreciable extension, the wire must be
(a) short and thin
(b) long and thick
(c) long and thin
(d) short and thick

The bulk modulus of a perfectly rigid body is
(a) one
(b) infinity
(c) zero
(d) none of the above