# Mechanical Properties of Solids and Fluids – Physics 8

## Mechanical Properties of Solids – Physics 8

1.Two wires Aand B are of the same material. Their lengths are in the ratio 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

(a)2 : 1

(b)1 : 4

(c)1 : 8

(d)8 : 1

2.When an elastic material with Young’smodulusY is subjected to stretching stress S, elastic energy stored per unit volume of the material is

(a)YS / 2

(b)S²Y / 2

(c)S²/ 2Y

(d)S / 2Y

3.The compressibility of water is 4× 10-5 per unit atmospheric pressure. The decrease in volume of 100 cm of water under a pressure of 100 atmosphere will be

(a)0.4 cm³

(b)4 × 10-5 cm³

(c)0.025cm³

(d)0.004 cm³

4.The following four wires are made of the same material. Which of these will have the largest extension when the same tension is applied?Mechanical Properties of Solids

(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

5.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

(a)7q/(5sp)

(b)5q/(7sp²)

(c)7q/(5sp²)

(d)2q/(5sp)

- Ans(3)
- Ans(3)
- Ans(1)
- Ans(4)
- Ans(3)

## Mechanical Properties of Fluids

1.The terminal velocity vr of a small steel ball of radius r falling under gravity through a column of a viscous liquid of coefficient of η viscosity depends on mass of the ball m, the acceleration due to gravity g, the coefficient of viscosity η and radius r. Which of the following relations is dimensionally correct?

(a)vr ∝ mgr/η

(b)vr ∝ mgrη

(c)vr ∝ mg/rη

(d)vr ∝ ηmg/r

2.In rising from the bottom of a lake, to the top, the temperature of an air bubble remains unchanged, but its diameter gets doubled. If his the barometric height (expressed in m of mercury of relative density ρ) at the surface of the lake, the depth of the lake, is

(a)8 ρh m

(b)7ρh m

(c)9 ρh m

(d)12 ρh m

3.The angle of contact between pure water and pure glass, is

(a)0º

(b)45º

(c)90º

(d)135º

4.A rectangular block of mass m and area of cross-section A floats in a liquid of density ρ. If it is given a small vertical displacement from equilibrium it undergoes oscillation with a time period T. Then

(a)T∝1/√A

(b)T∝1/ρ

(c)T∝1/√m

(d)T∝√ρ

5.The wettability of a surface by a liquid depends primarily on

(a)surface tension

(b)density

(c)angle of contact between the surface and the liquid

(d)viscosity

6.A fluid is in streamline flow across a horizontal pipe of the variable area of cross section. For this which of the following statements is correct?

(a)The velocity is minimum at the narrowest part of the pipe and the pressure is minimum at the widest part of the pipe

(b)The velocity is maximum at the narrowest part of the pipe and pressure is maximum at the widest part of the pipe

(c)Velocity and pressure both are maximum at the narrowest part of the pipe

(d)Velocity and pressure both are maximum at the widest part of the pipe

- Ans(3)
- Ans(2)
- Ans(1)
- Ans(1)
- Ans(3)
- Ans(2)

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