Class 11 Physics Chapter 9 Mechanical Properties of Solids Solved Questions and Answers

(1) A liquid is allowed to flow into a tube of truncated cone shape. Identify the correct statement from the following

[A] the speed is low at the wider end and high at the narrow end.

[B] the speed is high at the wider end and high at the narrow end

[C] the speed is same at both ends in a stream line flow.

[D] the liquid flows with uniform velocity in the tube.

Answer: the speed is low at the wider end and high at the narrow end.

(2) A uniform cube is subjected to volume compression. If each side is decreased by 1%, then bulk strain is

[A] 0.03

[B] 0.02

[C] 0.06

[D] 0.01

Answer: 0.03

(3) Beyond the critical speed, the flow of fluids becomes

[A] turbulent

[B] streamline

[C] steady

[D] very slow

Answer: turbulent

(4) For flow of a fluid to be turbulent

[A] both

[B] fluid should have high density

[C] velocity should be large

[D] None of these

Answer: both

(5) Assertion : Identical springs of steel and copper are equally stretched. More work will be done on the steel spring

Reason : Steel is more elastic than copper.

[A] Assertion is correct, reason is correct; reason is a correct explanation for assertion

[B] Assertion is correct, reason is correct; reason is not a correct explanation for assertion

[C] Assertion is correct, reason is incorrect

[D] Assertion is incorrect, reason is correct

Answer: Assertion is correct, reason is correct; reason is a correct explanation for assertion

(6) The reciprocal of the bulk modulus is called

[A] compressibility

[B] volume stress

[C] modulus of rigidity

[D] volume strain

Answer: compressibility

(7) Which of the following elastic moduli is used to describe the elastic behaviour of object as they respond to the deforming forces acting on them?

[A] All of these

[B] Shear modulus

[C] Young's modulus

[D] Bulk modulus

Answer: All of these

(8) The ratio of shearing stress to the corresponding shearing strain is called

[A] modulus of rigidity

[B] bulk modulus

[C] Young's modulus

[D] None of these

Answer: modulus of rigidity

(9) Which of the following affects the elasticity of a substance?

[A] Impurity in substance

[B] Change in temperature

[C] Hammering and annealing

[D] All of the above

Answer: All of the above

(10) Substances which can be stretched to cause large strains are called

[A] elastomer

[B] plastic

[C] ductile

[D] brittle

Answer: elastomer

(11) In magnitude hydraulic stress is equal to

[A] hydraulic pressure

[B] hydraulic strain

[C] hydraulic force

[D] restoring force

Answer: hydraulic pressure

(12) If the load is increased beyond the _______ point, the strain increases rapidly for even a small change in the stress

[A] yield point

[B] fracture point

[C] elastic point

[D] plastic point

Answer: yield point

(13) Which of the following is the correct relation? Y = Young's modulus & G = modulus of rigidity?

[A] Y > G

[B] None of these

[C] Y < G

[D] Y = G

Answer: Y > G.

(14) The Young’s modulus of a perfectly rigid body is

[A] infinity

[B] some finite non-zero constant

[C] zero

[D] unity

Answer: infinity

(15) The restoring force per unit area is known as

[A] stress

[B] plasticity

[C] elasticity

[D] strain

Answer: stress

(16) If the length of a wire is reduced to half, then it can hold the

[A] same load

[B] one fourth load

[C] half load

[D] double load

Answer: same load

(17) As the temperature of a liquid is raised, the coefficient of viscosity

[A] decreases

[B] increases

[C] remains the same

[D] may increase or decrease depending on the nature of liquid

Answer: decreases

(18) Shearing strain is expressed by

[A] angle of shear

[B] decrease in volume

[C] angle of twist

[D] increase in volume

Answer: angle of shear

(19) Longidudinal stress depends on

[A] area

[B] length

[C] volume

[D] mass

Answer: area

(20) According to Hooke’s law of elasticity, if stress is increased, then the ratio of stress to strain

[A] remains constant

[B] increases

[C] becomes zero

[D] decreases

Answer: remains constant

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NCERT Solutions for class 11 Physics | Chapter 9 - Mechanical Properties of Solids

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