Consider two wires X and Y. The radius of wire X is 3 times the radius of Y. If they are stretched by the same load then the stress on Y is

(a)

equal to that on X

(b)

thrice that on X

(c)

nine times that on X

(d)

Half that on X

If the temperature of the wire is increased, then the Young’s modulus will 

(a)

remain the same

(b)

decrease

(c)

increase rapidly

(d)

increase by very a small amount

A certain number of spherical drops of a liquid of radius R coalesce to form a single drop of radius R and volume V. If T is the surface tension of the liquid, then

(a)

energy = 4 V T \(\left( \frac { 1 }{ r } -\frac { 1 }{ R } \right) \)is released

(b)

energy = 3 V T \(\left( \frac { 1 }{ r } +\frac { 1 }{ R } \right) \)is absorbed

(c)

energy = 3 V T \(\left( \frac { 1 }{ r } -\frac { 1 }{ R } \right) \)is released

(d)

energy is neither released nor absorbed

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 = 200 cm, diameter = 0.5 mm

(b)

length= 200 cm, diameter = 1 mm

(c)

length = 200 cm, diameter = 2 mm

(d)

length= 200 cm, diameter = 3 m

In a horizontal pipe of non-uniform cross section, water flows with a velocity of 1 ms^-1 at a point where the diameter of the pipe is 20 cm. The velocity of water (1.5 m s^-1) at a point where the diameter of the pipe is (in cm)

(a)

8

(b)

16

(c)

24

(d)

32

The molar specific heats of an ideal gas at a constant pressure & volume are denoted by Cp&Cv if r =\(\frac{C_{p}}{C_{v}}\) & R the universal gases constant then C_v is equal _____________.

(a)

\(\frac{1+r}{1-r}\)

(b)

\(\frac{R}{1-r}\)

(c)

\(\frac{r-1}{R}\)

(d)

rR

Steam at 100°C is passed into 20g of water at 10°C when water acquires a temp of 80°C, the mass of water present will be ____________ (take specifies heat of water 1 cal g^-t c^-1 & latent heat of steam = 540 cal g^-1C^-1)

(a)

42.5 g

(b)

22.5g

(c)

24g

(d)

31.5g

Two metal wires of identical dimensions are connected in series if σ₁ and σ₂ are the conductivity of the metal wire respectively, the effective conductivity of the combination is ______________.

(a)

\(\frac{\sigma_{1}+\sigma_{2}}{2\sigma_{1}\sigma_{2}}\)

(b)

\(\frac{\sigma_{1}+\sigma_{2}}{\sigma_{1}\sigma_{2}}\)

(c)

\(\frac{\sigma_{1}\sigma_{2}}{(\sigma_{1}+\sigma_{2})}\)

(d)

\(\frac{2\sigma_{1}\sigma_{2}}{\sigma_{1}+\sigma_{2}}\)

Water rises in a capillary tube to a certain height such that the upward force due to the surface tension is balanced by 62.84\(\times\)10^-5N force due to the weight of the liquid column. If the surface tension of water is 70\(\times\)10^-3Nm the radius of the capillary tube is ____________.

(a)

1.43\(\times\)10^-3m

(b)

2.83\(\times\)10^-3 m

(c)

1.43\(\times\)10^-2 m

(d)

2.83\(\times\)10^-3 m

The work done against surface tension in blowing a soap bubble from a radjus of 5 cm to 15 cm is ____________. (surface tension of soap solution is 30\(\times\)10^-3 Nm^-1)

(a)

2.4 πmJ

(b)

4.8 π mJ

(c)

2.4 π J

(d)

4.8 π J