# MCQ Chapter Chapter 9 Mechanical Properties of Solids Class 11 Physics

Please refer to Mechanical Properties of Solids MCQ Questions Class 11 Physics below. These MCQ questions for Class 11 Physics with answers have been designed as per the latest NCERT, CBSE books, and syllabus issued for the current academic year. These objective questions for Mechanical Properties of Solids will help you to prepare for the exams and get more marks.

## Mechanical Properties of Solids MCQ Questions Class 11 Physics

Please see solved MCQ Questions for Mechanical Properties of Solids in Class 11 Physics. All questions and answers have been prepared by expert faculty of standard 11 based on the latest examination guidelines.

### MCQ Questions Class 11 Physics Mechanical Properties of Solids

Question. 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 these

D

Question. Minimum and maximum values of Possion’s ratio for a metal lies between
(a) – ∝ to + ∝
(b) 0 to 1
(c) – ∝ to 1
(d) 0 to 0.5

D

Question. The value of tan (90 – θ) in the graph gives

(a) Young’s modulus of elasticity
(b) compressibility
(c) shear strain
(d) tensile strength

A

Question. The length of an iron wire is L and area of corss-section is A. The increase in length is l on applying the force F on its two ends. Which of the statement is correct?
(a) Increase in length is inversely proportional to its length
(b) Increase in length is proportional to area of crosssection
(c) Increase in length is inversely proportional to area of cross-section
(d) Increase in length is proportional to Young’s modulus

C

Question. Two rods A and B of the same material and length have their radii r1 and r2 respectively. When they are rigidly fixed at one end and twisted by the same couple applied at the other end, the ratio

C

Question. A and B are two wires. The radius of A is twice that of B. They are stretched by the same load. Then the stress on B is
(a) equal to that on A
(b) four times that on A
(c) two times that on A
(d) half that on A

B

Question. The diagram shown below represents the applied forces per unit area with the corresponding change X (per unit length) produced in a thin wire of uniform cross section in the curve shown. The region in which the wire behaves like a liquid is

(a) ab
(b) bc
(c) cd
(d) Oa

B

Question. The Young’s modulus of a perfectly rigid body is
(a) unity
(b) zero
(c) infinity
(d) some finite non-zero constant

C

Question. Two wires of same material and length but cross-sections in the ratio 1 : 2 are used to suspend the same loads. The extensions in them will be in the ratio
(a) 1 : 2
(b) 2 : 1
(c) 4 : 1
(d) 1 : 4

B

Question. Hooke’s law defines
(a) stress
(b) strain
(c) modulus of elasticity
(d) elastic limit

C

Question. A body of mass 10 kg is attached to a wire of radius 3 cm. It’s breaking stress is 4.8 × 107 Nm–2, the area of cross-section of the wire is 10–6 m2. What is the maximum angular velocity with which it can be rotated in the horizontal circle ?

C

Question. A steel wire of length 20 cm and uniform cross-section 1 mm2 is tied rigidly at both the ends. The temperature of the wire is altered from 40ºC to 20ºC. Coefficient of linear expansion for steel a = 1.1 × 10–5/ºC and Y for steel is 2.0 × 1011 N/m2. The change in tension of the wire is
(a) 2.2 × 106 newton
(b) 16 newton
(c) 8 newton
(d) 44 newton

D

Question. A cube is subjected to a uniform volume compression. If the side of the cube decreases by 2% the bulk strain is
(a) 0.02
(b) 0.03
(c) 0.04
(d) 0.06

D

Question. A 2 m long rod of radius 1 cm which is fixed from one end is given a twist of 0.8 radian. The shear strain developed will be
(a) 0.002
(b) 0.004
(c) 0.008
(d) 0.016

B

Question. There are two wire of same material and same length while the diameter of second wire is two times the diameter of first wire, then the ratio of extension produced in the wires by applying same load will be
(a) 1 : 1
(b) 2 : 1
(c) 1 : 2
(d) 4 : 1

D

Question. The Young’s modulus of brass and steel are respectively 1010 N/m2. and 2 × 1010 N/m2. A brass wire and a steel wire of the same length are extended by 1 mm under the same force, the radii of brass and steel wires are RB and RS respectively. Then
(a) RS = √2 RB
(b) RS = RB / √2
(c) RS = 4RB
(d) RS = RB / 4

B

Question. For a given material, the Young’s modulus is 2. 4 times that of rigidity modulus. Its Poisson’s ratio is
(a) 2.4
(b) 1.2
(c) 0.4
(d) 0.2

D

Question. A cube at temperature 0ºC is compressed equally from all sides by an external pressure P. By what amount should its temperature be raised to bring it back to the size it had before the external pressure was applied. The bulk modulus of the material of the cube is B and the coefficient of linear expansion is a.
(a) P/B a
(b) P/3 B a
(c) 3 π a/B
(d) 3 B/P

B

Question. A circular tube of mean radius 8 cm and thickness 0.04 cm is melted up and recast into a solid rod of the same length. The ratio of the torsional rigidities of the circular tube and the solid rod is

A

Question. From a steel wire of density P is suspended a brass block of density Pb. The extension of steel wire comes to e. If the brass block is now fully immersed in a liquid of density Pl, the extension becomes e’. The ratio e/e’ will be

A

Question. On stretching a wire, the elastic energy stored per unit volume is
(a) Fl/2AL
(b) FA/2L
(c) FL/2A
(d) FL/2

A

Question. One end of a uniform wire of length L and of weight W is attached rigidly to a point in the roof and W1 weight is suspended from looser end. If A is area of cross-section of the wire, the stress in the wire at a height L/4 from the upper end is

B

Question. A wire fixed at the upper end stretches by length l by applying a force F. The work done in stretching is

D

Question. When a pressure of 100 atmosphere is applied on a spherical ball, then its volume reduces to 0.01%. The bulk modulus of the material of the rubber in dyne/cm2 is
(a) 10 × 1012
(b) 100 × 1012
(c) 1 × 1012
(d) 10 × 1012

C

Question. A massive stone pillar 20 m high and of uniform crosssection rests on a rigid base and supports a vertical load of 5.0 × 105 N at its upper end. If the compressive stress in the pillar is not to exceed 1.6 × 106 N m–2, what is the minimum cross-sectional area of the pillar? Density of the stone = 2.5 × 103 kg m–3. (Take g = 10 N kg–1)
(a) 0.15 m2
(b) 0.25 m2
(c) 0.35 m2
(d) 0.45 m2

D

Question. What per cent of length of wire increases by applying a stress of 1 kg weight/mm2 on it? (Y = 1 × 1011 N/m2 and 1 kg weight = 9.8 newton)
(a) 0.0067%
(b) 0.0098%
(c) 0.0088%
(d) 0.0078%

B

Question. The diagram below shows the change in the length X of a thin uniform wire caused by the application of stress F at two different temperatures T1 and T2. The variation shown suggests that

(a) T1 > T2
(b) T1 < T2
(c) T2 > T1
(d) T1 > T2

A

Question. 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

C

Question. A material has poisson’s ratio 0.50. If a uniform rod of it suffers a longitudinal strain of 2 × 10–3, then the percentage change in volume is
(a) 0.6
(b) 0.4
(c) 0.2
(d) Zero

D

Question. A 5 metre long wire is fixed to the ceiling. A weight of 10 kg is hung at the lower end and is 1 metre above the floor. The wire was elongated by 1 mm. The energy stored in the wire due to stretching is
(a) zero
(b) 0.05 joule
(c) 100 joule
(d) 500 joule

B

Question. A metalic rod of length l and cross-sectional area A is made of a material of Young modulus Y. If the rod is elongated by an amount y, then the work done is proportional to
(a) y
(b) 1/y
(c) y2
(d) 1/y2

C

Question. Two wires A and B are of the same material. Their lengths are in the ratio of 1 : 2 and the diameter are in the ratio 2 : 1. If they are pulled by the same force, then increase in length will be in the ratio of
(a) 2 : 1
(b) 1 : 4
(c) 1 : 8
(d) 8 : 1

C

Question. Two wires are made of the same material and have the same volume. However wire 1 has cross-sectional area A and wire 2 has cross-sectional area 3A. If the length of wire 1 increases by Δx on applying force F, how much force is needed to stretch wire 2 by the same amount?
(a) 4 F
(b) 6 F
(c) 9 F
(d) F

C

Question. The diagram shows a force – extension graph for a rubber band. Consider the following statements :
I. It will be easier to compress this rubber than expand it
II. Rubber does not return to its original length after it is stretched
III. The rubber band will get heated if it is stretched and released

Which of these can be deduced from the graph?
(a) III only
(b) II and III
(c) I and III
(d) I only

C

Question. A rod of length l and radius r is joined to a rod of length l/2 and radius r/2 of same material. The free end of small rod is fixed to a rigid base and the free end of larger rod is given a twist of q°, the twist angle at the joint will be
(a) θ/4
(b) θ/2
(c) 5θ/6
(d) 8θ/48

D

Question. In Searle’s experiment to find Young’s modulus the diameter of wire is measured as d = 0.05cm, length of wire is l = 125cm and when a weight, m = 20.0 kg is put, extension in wire was found to be 0.100 cm. Find maximum permissible error in Young’s modulus (Y). Use : 2
Y = mgl/(π /4) d2 x
(a) 6.3%
(b) 5.3%
(c) 2.3%
(d) 1%

A

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

D

Question. If the ratio of lengths, radii and Young’s modulus of steel and brass wires shown in the figure are a, b, and c, respectively. The ratio between the increase in lengths of brass and steel wires would be

D

Question. To break a wire, a force of 106 N/m2 is required. If the density of the material is 3 × 103 kg/m3, then the length of the wire which will break by its own weight will be
(a) 34 m
(b) 30 m
(c) 300 m
(d) 3 m

A

Question. A uniform cube is subjected to volume compression. If each side is decreased by 1%, then bulk strain is
(a) 0.01
(b) 0.06
(c) 0.02
(d) 0.03

D

Question. Modulus of rigidity of ideal liquids is
(a) infinity
(b) zero
(c) unity
(d) some finite small non-zero constant value

B

Question. The temperature of a wire is doubled. The Young’s modulus of elasticity
(a) will also double
(b) will become four times
(c) will remain same
(d) will decrease

D

Question. Copper of fixed volume ‘V; is drawn into wire of length ‘l’. When this wire is subjected to a constant force ‘F’, the extension produced in the wire is ‘Δl’. Which of the following graphs is a straight line?
(a) Δl versus 1/l
(b) Δl versus l2
(c) Δl versus 1/l2
(d) Δl versus l

B

Question. A rigid bar of mass M is supported symmetrically by three wires each of length l. Those at each end are of copper and the middle one is of iron. The ratio of their diameters, if each is to have the same tension, is equal to

B

Question. When a 4 kg mass is hung vertically on a light spring that obeys Hooke’s law, the spring stretches by 2 cms. The work required to be done by an external agent in stretching this spring by 5 cms will be (g = 9.8 m/sec2)
(a) 4.900 joule
(b) 2.450 joule
(c) 0.495 joule
(d) 0.245 joule

B

Question. A mild steel wire of length 2L and cross-sectional area A is stretched, well within elastic limit, horizontally between two pillars (figure ). A mass m is suspended from the mid-point of the wire. Strain in the wire is

A

Question. The approximate depth of an ocean is 2700 m. The compressibility of water is 45.4 × 10–11 Pa–1 and density of water is 103 kg/m3.What fractional compression of water will be obtained at the bottom of the ocean ?
(a) 1.0 × 10–2
(b) 1.2 × 10–2
(c) 1.4 × 10–2
(d) 0.8 × 10–2

B

Question. 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

D

Question. If the ratio of diameters, lengths and Young’s modulus of steel and copper wires shown in the figure are p, q and s respectively, then the corresponding ratio of increase in their lengths would be

C

Question. The following four wires are made of the same material. Which of these will have the largest extension when the same tension is applied ?
(a) Length = 100 cm, diameter = 1 mm
(b) Length = 200 cm, diameter = 2 mm
(c) Length = 300 cm, diameter = 3 mm
(d) Length = 50 cm, diameter = 0.5 mm