CBSE Class 11 Physics Mechanical Properties of Solids MCQs Set A

Question: 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

Question: The Young’s modulus of a perfectly rigid body is

a) infinity

b) some finite non-zero constant

c) zero

d) unity

Answer: infinity

Question: 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

Question: The restoring force per unit area is known as

a) stress

b) plasticity

c) elasticity

d) strain

Answer: stress

Question: In magnitude hydraulic stress is equal to

a) hydraulic pressure

b) hydraulic strain

c) hydraulic force

d) restoring force

Answer: hydraulic pressure

Question: Substances which can be stretched to cause large strains are called

a) elastomer

b) plastic

c) ductile

d) brittle

Answer: elastomer

Question: The reason for the change in shape of a regular body is

a) volume stress

b) shearing strain

c) longitudinal strain

d) metallic strain

Answer: volume stress

Question: Longidudinal stress depends on

a) area

b) length

c) volume

d) mass

Answer: area

Question: Which of the following affects the elasticity of a substance?

a) All of the above

b) Impurity in substance

c) Change in temperature

d) Hammering and annealing

Answer: All of the above

Question: 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

Question: 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

Question: 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

Question: 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

Question: The reciprocal of the bulk modulus is called

a) compressibility

b) volume stress

c) modulus of rigidity

d) volume strain

Answer: compressibility

Question: Which of the following statements is/are wrong?

I. Hollow shaft is much stronger than a solid rod of same length and same mass.

II. Reciprocal of bulk modulus of elasticity is called compressibility.

III. It is difficult to twist a long rod as compared to small rod.

a) III only

b) I only

c) II and III

d) I and II

Answer: III only

Question: 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

Question: 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

Question: 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

Question: The Poisson’s ratio of a material is 0.5. If a force is applied to a wire of this material, there is a decrease in the cross-sectional area by 4%. The percentage increase in the length is

a) 4%

b) 2.5%

c) 2%

d) 1%

Answer: 4%

Question: Modulus of rigidity of ideal liquids is

a) zero

b) infinity

c) unity

d) some finite small non-zero constant value

Answer: zero

Question: Beyond the critical speed, the flow of fluids becomes

a) turbulent

b) streamline

c) steady

d) very slow

Answer: turbulent

Question: Streamline flow is more likely for liquids with

a) low density and high viscosity

b) low density and high viscosity

c) high density and high viscosity

d) high density and high viscosity

Answer: low density and high viscosity

Question: 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

Question: In Bernoulli’s theorem which of the following is conserved?

a) Energy

b) Mass

c) Linear momentum

d) Angular momentum

Answer: Energy

Question: 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.

Question: 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

Question: After terminal velocity is reached, the acceleration of a body falling through a fluid is

a) zero

b) equal to g

c) less than g

d) greater than g

Answer: zero

Question: Terminal velocity of ball depends on

a) density difference of liquid and ball

b) density of ball only

c) density of liquid only

d) area of the ball

Answer: density difference of liquid and ball

Question: Surface tension of a liquid is due to

a) cohesive force between molecules

b) adhesive force between molecules

c) electrical force between molecules

d) gravitational force between molecules

Answer: cohesive force between molecules

Question: If a soap bubble formed at the end of the tube is blown very slowly, then the graph between excess pressure inside the bubble with time will be a

a) parabolic curve sloping down

b) parabolic curve sloping up

c) straight line sloping down

d) straight line sloping up

Answer: parabolic curve sloping down