## Class 11 Physics Objective Chapter – 9 Mechanical Properties of Solids

Here we are providing NCERT Class 11 Physics Objective Chapter – 9 Mechanical Properties of Solids Chapter Wise MCQs for board exam is very important for board exam preparation. This book explains all the concepts and topics in very simple language that the students can easily understand the complex subjects also. This NCERT Class 11 Physics MCQs Chapter – 9 Mechanical Properties of Solids Chapter consist all important topic regarding NCERT Class 11 Physics Objective Chapter – 9 Mechanical Properties of Solids. This book basically covers all the major and minor elements that together form a democratic government. Topics like power-sharing, federalism, democracy and diversity, political parties, consequences of democracy, challenges to democracy etc. have been discussed in the NCERT Class 11 Physics Objective Chapter – 9 Mechanical Properties of Solids. The question papers in CBSE board exams are generally based on the latest NCERT books. Hence, students must follow the NCERT book to prepare effectively for their Class 11 Physics exam. If you want color notes then click here

Class 11 Physics Objective Chapter – 9 Mechanical Properties of Solids

1. A member which does not regain its original shape after removal of the load producing deformation is said ______

( a ) Plastic

( b ) Elastic

( c ) Rigid

( d ) None of these

Ans:- (a)

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 × 10N/m²?

( a ) 2 mm²

( b ) 3 mm²

( c ) 4 mm²

( d ) 5 mm²

Ans:- (c)

3.The fractional change in volume per unit increase in the pressure is called :

( a ) Volume coefficient

( c ) Compressibility

( d ) Bulk modulus

Ans:- (c)

4.The breaking stress for wire of unit area of cross-section is called its

( a ) Young’s modulus

( b ) tensile strength

( c ) yield point

( d ) elastic limit

Ans:- (b)

5. 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

Ans:- (d)

6. A steel wire of length 20 cm and uniform cross-section 1mm2 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

Ans:- (d)

7. 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

Ans:- (d)

8. Hookes law essentially defines

( a ) Stress

( b ) Strain

( c ) Yield point

( d ) Elastic limit

Ans:- (d)

9. Which law is also called as the elasticity law?

( a ) Bernoulli’s law

( b ) Stress law

( c ) Hooke’s law

( d ) Poisson’s law

Ans:- (c)

10. Longitudinal strain is possible in the case of

( a ) Gases

( b ) Liquid

( c ) Only solids

( d ) Only gases & liquids

Ans:- (c)

11. 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

Ans:- (d)

12.If the length of a wire is reduced to half, then it can hold the

( b ) one fourth load

Ans:- (a)

13.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

Ans:- (b)

14. 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

Ans:- (d)

15. 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

Ans:- (c)

16. A body of mass 500 g is fastened to one end of a steel wire of length 2 m and area of cross section 2 mm². if the breaking stress of he wire is 1.25 × 107 N/m², then the maximum angular velocity with which the body can be rotated in a horizontal circle is

Ans:- (d)

17. Modulus of rigidity of ideal liquid is

( a ) infinity

( b ) zero

( c ) unity

( d ) some finite small non-zero constant value

Ans:- (b)

18. Out of the following materials, whose elasticity is independent of temperature?

( a ) Copper

( b ) Invar steel

( c ) Brass

( d ) Silver

Ans:- (b)

19.A wire of length L and radius r fixed at one end and a force F applied to the other end produces an extension l. The extension produced in another wire of same material of length 2L and radius 2r by a force 2F is given by

( a ) l

( b ) 2l

( c ) l/2

( d ) 4l

Ans:- (a)

20.The substance which shows no elastic after effect practically is

( a ) steel

( b ) rubber

( c ) copper

( d ) quartz

Ans:- (d)

21. A rubber cord of cross sectional area 1mm² 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

Ans:- (c)

22.A wire suspended vertically from one of its ends is stretched by attaching a weight of 200N to the lower end. The weight stretches the wire by 1 mm. Then the elastic energy stored in the wire is

( a ) 0.2 J

( b ) 10 J

( c ) 20 J

( d ) 0.1 J

Ans:- (d)

23.Out of the following materials, whose elasticity is independent of temperature?

( a ) Copper

( b ) Invar steel

( c ) Brass

( d ) Silver

Ans:- (b)

24.If a material is heated and annealed, then its elasticity is

( a ) Increased

( b ) Decreased

( c ) Not change

( d ) Becomes zero

Ans:- (b)

25.Longitudinal strain is possible in the case of

( a ) Gases

( b ) Liquid

( c ) Only solids

( d ) Only gases & liquids

Ans:- (c)

26.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

( b ) Elongation is directly proportional to cross section A

( c ) Elongation is inversely proportional to A

( d ) Elongation is directly proportional to Youngs modulus

Ans:- (c)

27. 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

Ans:- (c)

28.The change in the shape of a regular boy is due to

( a ) Bulk strain

( b ) Shearing strain

( c ) Longitudinal strain

( d ) Volume strain

Ans:- (b)

29. Out of the following materials, whose elasticity is independent of temperature

( a ) Copper

( b ) Invar steel

( c ) Brass

( d ) Silver

Ans:- (b)

30.A metal rod of Young’s modulus 2 × 1010 N m–2 undergoes an elastic strain of 0.06%. The energy per unit volume stored in J m–3 is

( a ) 3600

( b ) 7200

( c ) 10800

( d ) 14400

Ans:- (a)

31. 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

Ans:- (c)

32. 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

Ans:- (c)

33.When impurities are added to an elastic substance, its elasticity

( a ) Increases

( b ) Decreases

( c ) Becomes zero

( d ) Remains constant

Ans:- (a)

34.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

Ans:- (c)

35.A cable breaks if stretched by more than 2 mm. It is cut into two equal parts. By how much either part can be stretched without breaking?

( a ) 2mm

( b ) 1 mm

( c ) 0.5 mm

( d ) 0.25 mm

Ans:- (b)

36.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

Ans:- (c)

37.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

Ans:- (c)

38.A force of 103 newton, stretches the length of a hanging wire by 1 millimetre. The force required to stretch a wire of same material and length but having four times the diameter by 1 millimetre is

( a ) 4 × 103 N

( b ) 16 × 103 N

( c ) 1/4 x 103 N

( d ) 1/16 x 103N

Ans:- (b)

39.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

Ans:- (a)

40. A wire suspended vertically from one of its ends is stretched by attaching a weight of 100N to its lower end. What is the elastic potential energy stored in the wire, if the weight stretches the wire by 1.5 mm?

( a ) 5 × 10-2 J

( b ) 10-3 J

( c ) 2.5 × 10-3 J

( d ) 7.5 × 10-2 J

Ans:- (d)

41. Shearing strain is expressed by

( a ) angle of shear

( b ) decrease in volume

( c ) angle of twist

( d ) increase in volume

Ans:- (a)

42. 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

Ans:- (a)

43.In the following data, the fou r 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

Ans:- (a)

44.In magnitude hydraulic stress is equal to

( a ) hydraulic pressure

( b ) hydraulic strain

( c ) hydraulic force

( d ) restoring force

Ans:- (a)

45.If the length of a wire is reduced to half, then it can hold the

( b ) one fourth load

Ans:- (a)

46.Which one of the following is not a unit of Young’s modulus ?

( a ) Nm–1

( b ) Nm–2

( d ) dyne cm–2

( d ) mega pascal

Ans:- (a)

47.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

Ans:- (c)

48.Theoretical value of Poissions ratio lies between

( a ) -1 to 0.5

( b ) -1 to -2

( c ) 0.5 to 1

( d ) None

Ans:- (a)

49. The property by which a body returns to its original shape after removal of the force is called ______

( a ) Plasticity

( b ) Elasticity

( c ) Ductility

( d ) Malleability

Ans:- (b)

50. 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 × 10N/m²

( d ) 32 × 106 N/m²

Ans:- (d)