IISER Physics - Properties of Matter
Exam Duration: 45 Mins Total Questions : 30
Two steel wires have their lengths and diameters in the ratio of 1 : 2. Their elongation for the same stretching force will be in the ratio
- (a)
1 : 4
- (b)
4 : 1
- (c)
1 : 2
- (d)
2 : 1
A vertical wire 2.0 m long and 2.0 \(\times\) \(10^{-6}m^{2}\) in cross-section is found to stretch 0.003 m under a load of 40 N at its lower end. Assuming Hooke's law holds, the molecular potential energy in J of the streched wire is
- (a)
0.024
- (b)
0.048
- (c)
0.060
- (d)
0.6
Choose correct statement :
- (a)
Metals have high young modulus and low elastic strain
- (b)
Glass has young modulus and low elastic strain
- (c)
Plastics are less stiff and do not obey Hooke's law like metals do
- (d)
All of the above
Which of the statements on rubber and glass is correct ?
- (a)
Rubber has a low strain when initially stretched
- (b)
Rubber has no energy when stretched
- (c)
Glass has no dislocation
- (d)
Th stress-strain surves of two materials are similar
A ship,floating in clear water of density 1000 kg m-3 moves to sea-water of density1050 kg m-3 where it floats again.The upthrust on the ship then
- (a)
increases by 0.05 times
- (b)
decreases by 0.05 times
- (c)
stays constant
- (d)
first increases and then stays constant
A beaker contains two liquids of specific gravity p1 and p2.A body of specific gravity p floats in this mixture of immiscible liquids.What fraction of its volume is in liquid of specific gravity p1?
- (a)
\(\frac{\rho_1}{\rho_2}\)
- (b)
\((1-\frac{\rho_1}{\rho_2})\)
- (c)
\(\frac{\rho_1-\rho}{\rho_1-\rho_2}\)
- (d)
\(\frac{\rho-\rho_2}{\rho_1-\rho_2}\)
The mean free path of a gas molecule is inversely proportional to
- (a)
molecular diameter
- (b)
square of molecular diameter
- (c)
fourth power of molecular diameter
- (d)
square root of the molecular diameter
An odd shaped body when immersed in water weighs 980 N and when immersed in kerosene (relative density = 0.80) weighs 1127.76 N.Then relative density of the body must be
- (a)
0.23
- (b)
0.32
- (c)
1.89
- (d)
none of these
A vessel at 76 cm Hg and of volume V is connected to another vessel which has vaccum and whose volume is 3V.The resultant pressure (in cm Hg) is
- (a)
25
- (b)
19
- (c)
38
- (d)
76
An object is floating in a beaker of water.If taken from one place to another where the acceleration of gravity g is substantially different,the depth of submersion of the floating object
- (a)
will remain the same
- (b)
will decreases if g decreases
- (c)
will increases if g decreases
- (d)
depends on the density of the object
Two wires of equal length are made of same material.Wire A has a diameter that is twice that of wire B.If identical weights are suspended from the ends of these wires,the increase in length is
- (a)
four times for wire A as for wire B
- (b)
twice for wire A as for wire B
- (c)
half for wire A as for wire B
- (d)
one-fourth for wire A as for wire B
A wire of length L and radius r is rigidly fixed at one end.On stretching the other end of the wire with a force F, the increase in its length is l.If another wire of same material but of length 2L and radius 2r is stretched with a force 2F, the increase in its length will be
- (a)
l/4
- (b)
l/2
- (c)
l
- (d)
2l
If 'S' is stress and 'Y' is Young's modules of material of a wire,then the energy stored in the wire per unit volume is
- (a)
\(\frac{S^2}{2Y}\)
- (b)
\(\frac{2Y}{S^2}\)
- (c)
\(\frac{S}{2Y}\)
- (d)
\(2S^2Y\)
Hooke's law essentially defines
- (a)
stress
- (b)
strain
- (c)
yield point
- (d)
elastic limit
An inflated balloon rises to a definite height once it starts going up.This balloon cannot rise any further because at that height
- (a)
atmospheric pressure reduces to zero
- (b)
acceleration due to gravity is reduced to zero
- (c)
density of balloon reduces to zero
- (d)
apparent weight of balloon is zero
A metallic sphere floats in an immiscible mixture of water (\(\rho_w = 10^3\ kg\ m^-3\)) and a liquid (\(\rho_L = 13.5 \times 10^3\ kg\ m^-3\)) such that its \(\frac{4}{5}\)th portion is in water and \(\frac{1}{5}\)th portion is in the liquid.The density of the liquid in kg m-3 is
- (a)
4.5 x 103
- (b)
4 x 103
- (c)
3.5 x 103
- (d)
3.0 x 103
Two soap bubbles of radii r1 and r2 are joined together by thin surface.The radii of the two bubbles together is
- (a)
r1 + r2
- (b)
\(\frac{r_1 + r_2}{2}\)
- (c)
\(\frac{r_1 r_2}{r_1 + r_2}\)
- (d)
\(\frac{r_1 + r_2}{r_1r_2}\)
A soap bubble in vacuum has a radius of r1 and another soap bubble in vacuum has a radius of r2.If two bubbles coalesce under isothermal conditions then the radius of the new bubble is
- (a)
R = r1 + r2
- (b)
R = r1 - r2
- (c)
\(R = \sqrt {r_1^2 + r_2^2}\)
- (d)
\(R = \sqrt {r_1^2 - r_2^2}\)
the potential energy of a molecule on the surface of a liquid compared to one inside the liquid is
- (a)
zero
- (b)
smaller
- (c)
the same
- (d)
greater
Two capillary tubes of radii 0.2 cm and 0.4 cm are dipped in the same liquid.The ratio of heights through which liquid will rise in the tubes is
- (a)
1 : 2
- (b)
2 : 1
- (c)
1 : 4
- (d)
4 : 1
If we dip capillary tubes of different radii in water and water rises to different heights h in them,then
- (a)
\(\frac{h}{r^2}\) = constant
- (b)
\(\frac{h}{r}\) = constant
- (c)
hr = constant
- (d)
\(hr^2\) = constant
Water rises in a capillary tube due to
- (a)
viscosity
- (b)
diffusion
- (c)
density
- (d)
surface tension
A glass rod is dipped in mercury and withdrawn out,the mercury does not wet the rod because
- (a)
angle of contact is acute
- (b)
cohesion force is more
- (c)
adhesion force is more
- (d)
density of mercury is more
Water rises in a capillary tube to a certain height such that the upward force of surface tension is balanced by the downward weight of liquid 75 x 10-4 N.The inner radius of the capillary will be [surface tension, T = 0.06 Nm-1]
- (a)
1.25 x 10-2 m
- (b)
0.99 x 10-2 m
- (c)
1.99 x 10-2 m
- (d)
1.59 x 10-2 m
Two waterpipes P and Q having diameters 2 x 10-2 m and 4 x 10-2 m respectively are joined in series with the main supply line of water.The velocity of water flowing in pipe P is
- (a)
4 times that of Q
- (b)
2 times that of Q
- (c)
1/2 times that of Q
- (d)
1/4 times that of Q
Water from a tap(at the end of a horizontal pipe) emerges vertically downwards with an initial speed of 1.0 ms-1.The cross-sectional area of the tap is 10-4 m2.Assume that the pressure is constant throughout the stream of water and the flow is steady,the cross-sectional area of the stream 0.15 m below the tap is (g = 10 ms-2).
- (a)
5.0 x 10-4 m2
- (b)
1.0 x 10-5 m2
- (c)
5 x 10-5 m2
- (d)
2.0 x 10-5 m2
Bernoulli's principle for non-viscous,incompressible fluid is based on the conservation of
- (a)
mass
- (b)
momentum
- (c)
kinetic energy
- (d)
energy
22 g of CO2 at 27°C is mixed with 16 g of O2 at 37°C.The temperature of mixture is
- (a)
27°C
- (b)
30.5°C
- (c)
32°C
- (d)
37°C
According to kinetic theory of gases,which one of the follwing statements is NOT correct?
- (a)
Real gas behaves as an ideal gas at high temperature and low pressure
- (b)
Liquid state of ideal gas is impossible
- (c)
At any temperature and pressure ideal gas obeys the Boyle's and Charle's law
- (d)
The molecules of real gas do not exert any force on one another
The average kinetic energy of a gas molecule at 27°C is 6.21 x 10-2 J.Its average kinetic energy at 227°C will be
- (a)
52.2 x 10-21 J
- (b)
5.22 x 10-21 J
- (c)
10.35 x 10-21 J
- (d)
11.35 x 10-21 J