A K CHILDREN ACADEMY, RAJ NAGAR EXTN.

SESSION 2021-22; REVISION WORKSHEET

SUBJECT Physics (042), CLASS XI

CHAPTER 9 (MECHANICAL PROPERTIES OF SOLIDS)

1. The elastic limit of a steel cable and a copper wire of equal length and equal cross-sectional area are joined end
to end and the combination is subjected to a tension. Find the ratio of (a) the stress developed in the two wires (b)
the strain developed in the two wires. Given Ysteel = 2.0×1011 N/m2 & Ycopper = 1.1×1011 N/m2.

2. What force is required to stretch a steel wire 1cm2 in cross section to double its length? Ysteel = 2×1011Nm-2.

3. The mass of a lift is 2000 kg and it is fastened by thick wires of iron. If the maximum acceleration of the lift be
1.2 m/s2 and the maximum safe stress of wire be 2.8 x 108 N/m2, then what should be the minimum diameter of the
wire? g = 9.8 m/s2.

4. A rubber ball is taken at a depth of 300 m in a deep lake. Its volume decreases by 0.15%. Calculate the bulk
modulus of elasticity of rubber. The density of water of lake is 1.0×103kg/m3 and g = 10m/s2.

5. Find the change in volume which 1 cm3 of water will undergo when it is taken from the free surface to the
bottom of the lake 300m deep. Given the bulk modulus is 22,000 atm.

6. Two identical solid balls, one of ivory & the other of wet-clay, are dropped from the same height on the floor.
Which will rise to a greater height after striking the floor and why?

7. The ratio stress/strain remains constant for small deformation. What will be the effect on this ratio when the
deformation made is very large?

odulus?

9. Define stress.

10.

11.

12. Two wires of same material and length are stretched by the same force. Their masses are in the ratio 3:2. Find
the ratio of their elongations.

13. ×1012N/m2 and there is no transverse strain in it. Find its

modulus of rigidity?

14. Explain why solids are more elastic than gases?

15. A long spring is stretched by 2 cm and its potential energy is V. Find the potential energy of the spring if it is
stretched by 10 cm?

16. Forces of 105 N each are applied in opposite directions on upper and lower faces of a cube of side 10cm,
shifting the upper face parallel to itself by 0.5cm. If the side of the cube were 20cm, what would be the
displacement?

17. A 14.5 kg mass, fastened to the end of a steel wire of unstretched length 1m, is whirled in a vertical circle with
an angular velocity of 2 rev/sec at the bottom of the circle. The cross-sectional area of the wire is 0.065cm2.
Calculate the elongation of the wire when the mass is at the lowest point of its path. Ysteel=2 1011 N/m2.
18.
19. What is the value of modulus of rigidity for a liquid?

20. A wire 3 m in length suspended vertically stretches by 1 mm when mass of 40 kg is attached to the lower end.
What is the potential energy gained by the wire?

21. The breaking stress of aluminum is 8.1 107 Nm-2. Find the greatest length of aluminum wire that can hang
vertically without breaking. Density of aluminum is 2.7 103 kgm-3.

22. Two wires A and B of the same material have radii in the ratio 2:1 and lengths in the ratio 4:1. Find the ratio of
the normal forces required to produce the same change in the lengths of the two wires?

23. A rod elongates by l when a body of mass m is suspended from it. Find the work done in the process?

24. A copper and a steel wire of same length and cross section are attached end to end. The compound wire is hung
from a rigid support and a load is suspended from the free end. If Y of steel is (20/9) times of copper then find the
ratio of increase in length of steel wire to copper wire?

25. Compute the fractional change in volume of a glass slab, when subjected to a hydraulic pressure of 1 atm. It is
given bulk modulus of glass = 37 109 Nm-2

26. One end of a wire 2m long and diameter 2mm is fixed in the ceiling. A naughty boy of mass 10kg jumps to
catch the free end and stays there. Find the change in the length of the wire. Y= 1011 N/m2

27. In the following stress strain curve, which has:-

c) More Tensile
strength.

28. A cube is subject to a pressure of 5×105 Nm-2. Each side of

cube is shortened by 1% find:
1) the volumetric strain 2) the bulk modulus of elasticity of cube.

30. What are ductile and brittle materials?

31. An elastic wire is cut to half its original length. How would it affect the maximum load that the wire can
support?

32. Define modulus of elasticity and write its various types

33. Which is more elastic rubber or steel? Explain.

s modulus of steel is 2×1011 N/m2. If the interatomic spacing for the metal is 2.8×10-10m, find the
increase in the interatomic spacing for a force of 109 N/m2 and the force constant?

CHAPTER 10 (MECHANICAL PROPERTIES OF FLUIDS)

1. A hole of area 4 cm2 is formed in the side of a ship 2.4 m below the water level. What minimum force is
required to hold on a patch covering the hole from the inside of the ship? Given that the density of sea water = 1.03
X 103 kg/m3.
2. A soap bubble is formed at one end, and a smaller soap bubble at the other end of a bent tube. Which of the
bubbles will expand and why?

3. A flask contains glycerin & the other contains water. Both are stirred vigorously & placed on the table. In which
flask will the liquid come to rest earlier & why?

4. Deduce an expression for the excess pressure inside a soap bubble.

5. Wings of an Aeroplan helps it to rise high against gravity. Explain.

6. An air bubble of radius 0.1mm is moving upwards in water with a velocity of 0.35 cm/s. If the density of water
is 1.0 x 103 kg/m3 and gravitational acceleration is 9.8m/s2 and the density of the air is negligible, then find out the
coefficient of viscosity of water.

7. What is the effect of impurities on the surface tension of liquid?

8. Water is flowing through two horizontal pipes of different diameters which are connected together. In the first
pipe the speed of water is 4.0 m/s & the pressure is 2.0 x 104 N/m2. Calculate the speed & pressure of water in the
second pipe. The diameters of the pipes are 3.0 cm & 6.0 cm respectively.

9. What happens to the surface tension of the liquid when temperature is increased?

10. What is surface energy?

11. What will be the acceleration of a body falling through a viscous medium after terminal velocity is reached?

12. Explain why the blood pressure in humans is greater at the feet than at the brain.

13. Explain why surface tension of the liquid is independent of the area of contact of the liquid surface.

14. Explain why we should blow over the paper to keep it horizontal.

15. The level of water in a tank is 5 m high. A hole of area 1 cm2 is made at the bottom of the tank. Find the rate of
leakage of water from the hole?

16. Water is flowing in a river. If the velocity of a layer at a distance 10 cm from the bottom is 20 cm/sec, find the
velocity of layer at a height of 40 cm from the bottom?

17. What is a streamline flow?

18. What is surface tension? Give its unit.

19.

20. What is capillarity?

21. The excess pressure inside a soap bubble of radius 4 cm is 30 dyne/cm2.Find the surface tension?

22. A 40kg girl wearing high heel shoes balances on a single heel. The heel is circular with diameter 2cm. What is
the pressure exerted by the heel on the horizontal floor?

23. The excess pressure inside a soap bubble is twice the excess pressure inside a second soap bubble. The volume
24. Find the work done by a boy in making soap bubble of diameter 1.4 cm by blowing. Surface tension of soap
bubble is 0.03N/m.

25. The cylindrical tube of a spray pump has a cross section of 8.0cm2, one of which has 40 fine holes each of
diameter 1.0mm. If the liquid flows inside the tube at the rate of 1.5m per minute, what is the speed of ejection of
the liquid through the holes?

26. State the principle on which Hydraulic lift work and explain its working?

27. At what depth in an ocean will a tube of air have one fourth volume it will have on reaching the surface?
Given Atmospheric Pressure = 76 cm of Hg and density of Hg = 13.6g/cc?

28. Why is it painful to walk barefooted on a road covered with pebbles having sharp edges?

29. Water rises in a capillary tube but mercury falls in the same tube. Why?

30. What should be the pressure inside a small air bubble of 0.1mm radius situated just below the water surface?
Surface tension of water = 7.2 × 10-2 N/m and atmospheric pressure = 1.013 × 105 N/m2?

31. Why is a soap solution a better cleansing agent than ordinary water?

32. What is terminal velocity? What is the terminal velocity of a body in a freely falling system?

33. The diameter of ball A is half that of ball B. What will be their ratio of their terminal velocities in water?

34. Find out the dimensions of co-efficient of viscosity?

35. What is the cause of viscosity in a fluid? How does the flow of fluid depend on viscosity?

36. If eight rain drops each of radius 1 mm are falling through air at a terminal velocity of 5 cm/s. If they coalesce
to form a bigger drop, what is the terminal velocity of bigger drop?

37. Why does the cloud seem floating in the sky?

38. A metal plate 5cm×5cm rests on a layer of castor oil 1 mm thick whose coefficient of viscosity is 1.55 Nsm-2.
What is the horizontal force required to more the plate with a speed of 2 cm/s?

39. A metallic sphere of radius 1×10-3 m and density 1×104 kgm-3 enters a tank of water after a free fall through a

h. Given :-
Co-efficient of viscosity of water = 1×10-3 Ns/m2; g = 10 m/s2; density of water = 1×103 kg/?

40. What is law and what are the factors on which viscous drag depends?
41. Water flows through a horizontal pipe of which the cross section is not constant. The pressure is 1cm of
mercury where the velocity is 0.35m/s. Find the pressure at a point where the velocity is 0.65m/s.

42. What is terminal velocity and derive an expression for it?

43. What is equation of continuity? Water plows through a horizontal pipe of radius, 1cm at a speed of 2m/s. What
should be the diameter of nozzle if water is to come out at a speed of 10m/s?
44 pressure, potential and kinetic energy in the streamline flow is
constant?

45. Two pipes P and Q having diameters 2×10-2 m and 4×10-2 m respectively are joined in Series with the main
supply line of water. What is the velocity of water flowing in pipe P?

46. A horizontal pipe of diameter 20 cm has a constriction of diameter 4 cm. The velocity of water in the pipe is
2m/s and pressure is 10 N/m2. Calculate the velocity and pressure at the constriction?

47. The reading of a pressure metre attached to a closed is 2.5×105 N/m2. On opening the valve of pipe, the reading
of the pressure metre reduces to 2.0×105 N/m2. Calculate the speed of water flowing through the pipe?

48. A large bottle is fitted with a siphon made of capillary glass tubing. Compare the Co-efficient of viscosity of
water and petrol if the time taken to empty the bottle in the two cases is in the ratio 2:5. Given specific gravity of
petrol = 0.8

CHAPTER 11 (THERMAL PROPERTIES OF MATTER)

1. The coefficient of volume expansion of glycerin is 49 10-5/ C. Find the fractional change in its density for
30 C rise in temperature.

2. How does the density of a solid affected when the solid is heated? Derive the mathematical relation.

3. The brass scale of barometer gives correct reading at 0 C. Coefficient of linear expansion of Brass is 2.0×10-
5
/ C. The barometer reads 75.00 cm at 27 C. what is the true atmospheric pressure at 27 C?

4. At 0 C, the mass of 1.000m3 volume of mercury is 13,600 kg. Find the density of mercury at 100 C. The
coefficient of cubical expansion of mercury is 1.8×10-4 C.

5. When a drop of water falls on a very hot iron, it takes quite long to evaporate. Why?

6. We take our right hand 5 cm above 500 W live bulb, and the left hand at the same distance below the bulb. The
right hand feels more heat. Why?

7. Calculate the difference in temperatures between two sides of an iron plate 20 mm thick, when heat is conducted
at the rate of 6×105 cal.min-1m-2K for metal is 0.2 cal s-1cm-1K-1.

8. A specific gravity glass bottle is marked with its volume along with a temperature. Why?

9. What is heat?

10. Define specific heat.

11. What is meant by triple point?

12. A piece of metal has a length 30 cm at 15 C. At 90 C its length increases by 0.027 cm. Find the coefficient of
cubical expansion of the metal?

13. Explain why water does not freeze at the bottom of the lakes in winter.

14. It is required to prepare a steel meter scale, such that the millimeter intervals are to be accurate within 0.0005
mm at a certain temperature. Determine the maximum temperature variation allowable during the rulings of
millimeter marks. Given for steel = 1.322 10-5 C-1
15. A person weighing 60 kg takes in 2000 kcal diet in a day. If this energy were to be used in heating the person
without any losses, what would be his rise in temperature? Given specific heat of human body is 0.83 cal g-1 C-1

16. If I is the moment of inertia of a solid body, find the change in I corresponding to a small change in
temperature?

17. Two vessels of volumes 5 and 3 litres contain air at pressure of 3 and 7 atmospheres, respectively. What will
be the resultant pressure when they are connected through a small-bore tube? Assume temperature remains
constant throughout.
18. Name the thermometers which are used to measure very high temperature.

19. Define specific heat of a gas at constant volume.

20. What is a trade wind?

21. How is skating possible on snow?

22. A cube of ice is placed on a bimetallic strip at room temperature as

shown in the fig. What will happen if the upper strip is of iron and
lower strip is of copper?
23. A platinum resistance thermometer has resistanc C and

the bath on the platinum resistance thermometer?

24.

25. How much should the temperature of a brass rod be increased so as to increase its length by 1%? Given for
brass is 0.00002 C-1

26. A pendulum clock having copper rod keeps correct time at 20 C. It gains 15 seconds per day if cooled to 0 C.
Calculate the coefficient of linear expansion of copper.

27. A thermometer has wrong calibration. It reads the melting point of ice as 20 0C. It reads 70 0C in place of 50
0
C. What is the temperature of boiling point of water on the scale?

28. Write the advantages and disadvantages of platinum resistance thermometer?

29. If the volume of block of metal changes by 0.12% when it is heated through 20 0C. What is the co-efficient of
linear expansion of the metal?

30. The density of a solid at00C and 500 0C is in the ratio 1.027:1. Find the coefficient of linear expansion of the
solid?

31. If one Mole of a monatomic gas is mixed with 3 moles of a diatomic gas. What is the molecular specific heat
of the mixture at constant volume?

32. Calculate Cp for air, given that Cv =0.162 cal g-1 k-1and density air at N.T. P is 0.001293 g/cm3?

33. Develop a relation between the co-efficient of linear expansion, co-efficient superficial expansion and
coefficient of cubical expansion of a solid?
34. Calculate the amount of heat required to convert 1.00kg of ice at 10 0c into steam at 100 0c at normal
pressure. Specific heat of ice = 2100 J/kg-K. Latent heat of fusion of ice = 3.36×105 J/kg, specific heat of water =
4200 J/kg-K. Latent heat of vaporization of water = 2.25×106 J/kg?

35. Show that Cp - CV = R Where [Cp = specific heat at constant pressure ; CV = specific heat at constant volume
and R = Universal Gas constant] for an ideal gas?

36. How do you justify that when a body is being heated at melting point, the temperature remains Constant?

37. On a winter night, you feel warmer when clouds cover the sky than when sky is clear. Why?

38. If a body is heated from 27 0C to 927 0C then what will be the ratio of energies of radiation emitted?

39. Two conducting slabs of thermal conductivities K1 and K2 are joined as shown in the figure. The temperature
1 2 1 2 m)?

40. Differentiate between conduction, convection and radiation?

41. The tile floor feels colder than the wooden floor even though both floor materials are at same temperature.
Why?

42

43. Define the terms reflectance, absorptance and transmittance. How are they related?

44. Discuss briefly energy distribution of a black body radiation. Hence deduce
CHAPTER 12 (THERMODYNAMICS)
1. A block of ice is dropped from a height h. One-tenth of its mass melts when it strikes the ground. Calculate h.
Latent heat of ice = 3.4×105 J/kg, g = 10 N/kg.

2. Write the sign conventions for the heat and work done during a thermodynamic process?

3. When we rub our hands together, they are warmed but only upto a final maximum temperature. Why?

4. Assuming an ordinary domestic refrigerator to be ideal one working between the temperature of melting ice and
that of atmosphere (300K), calculate the energy which must be supplied to it to freeze 1 kg of water at 0 C. Given
that latent heat of ice = 3.33×105 J/kg.

5. Calculate the rise in temperature of water which falls from a height 100 m, if 80% of the energy due to fall is
converted into heat and retained by water. (J = 4.2 J/cal, g = 9.8 m/s2)

6. Find the amount of work done to increase the temperature of one mole of an ideal gas by 30 0C, if it is
2/3
. Given R = 1.99 cal/(mol - K).

7. Calculate the work done during the isothermal Process?

8. What is an adiabatic process?

9. What is an isothermal process?

10. Deduce the work done in the following complete cycle?

11. A certain gas at atmospheric pressure is compressed adiabatically so that its volume becomes half of its
original volume. Calculate the resulting pressure?

12. State Kelvin-Planck statement of second law of thermodynamics.

13. How does second law of thermodynamics explain expansion of gas?

14. What amount of heat must be supplied to 2×10-2 kg of nitrogen at room temperature to raise its temperature by
45 C at constant pressure? Given molecular mass of nitrogen is 28 and R = 8.3 Jmole-1K-1

15. Which thermodynamic variable is defined by (a) Zeroth law of thermodynamics (b) First law of
thermodynamics?

16. An ideal gas is compressed at a constant temperature, will its internal energy increase or decrease?

17. Can whole of heat be converted into work?

18. What is zeroth law of thermodynamics?

19. What is internal energy of a system?

20. What is Clausius statement of second law of thermodynamics?

21. State first law of thermodynamics.

22. Explain why two bodies at different temperatures T1 and T2, if brought in thermal contact do not necessarily
settle to the mean temperature (T1 + T2)/2 ?

23. A sample of ideal gas( = 1.4) is heated at constant pressure. If an amount of 140 J of heat is supplied to the
gas, find (a) change in internal energy of the gas (b) work done by the gas?

24. Why is conversion of heat into work not possible without a sink at lower
temperature?

CHAPTER -14 (OSCILLATIONS )

1. A body of mass 0.4 kg when suspended by an ideal spring increases the
length of the spring by 2 cm. What will the time period when a body of 2 kg is
suspended by this spring?

2. The acceleration of a particle executing SHM is 20 cm/s2 at a distance 5 cm from its equilibrium position.
Calculate its time period.

3. What is the difference between forced vibrations and resonant vibrations?

4. The periodic time of a body executing SHM is 2 s. After how much interval from t=0, will its displacement be
half of its amplitude?

5. What do you understand by restoring force acting on a vibrating body? Give its one example.

6. The acceleration due to gravity on the surface of moon is 1.7 m/s2. What is the time period of simple pendulum
on the surface of moon if its time period on the surface of the earth is 3.5 s?

7. When an army crosses a suspension bridge then the soldiers break steps, why?

8. A particle executing SHM of period 8 s. After what time of its passing through the mean position will the
energy be half kinetic and half potential?

9. At what distance from the mean position, is the kinetic energy in a simple harmonic oscillator equal to potential
energy?

10. A simple harmonic oscillator is represented by the equation : Y = 0.40 Sin(440t) Y is in metres t is in seconds
Find the values of 1) Amplitude 2) Angular frequency 3) Frequency of oscillation 4) Time period of oscillation, 5)
Initial phase.

11. The soldiers marching on a suspended bridge are advised to go out of steps. Why?

12. The springs of spring factor K, 2K, K respectively are connected in parallel to a mass m. If the mass = 0.08kg
m and k = 2N/m, then find the new time period?

13. An 8 kg body performs S.H.M. of amplitude 30 cm. The restoring force is 60N, when the displacement is
30cm. Find: - a) Time period b) the acceleration c) potential and kinetic energy when the displacement is 12cm?

14. A pendulum clock is observed to give correct time at the equator. What will happen if the same pendulum
clock is taken to the pole of the earth?
15. A mass m is vertically suspended from a spring of negligible mass. The system oscillates with a frequency v.
Find the frequency of the system if a mass 4m is suspended from the same spring?

16. If the period of oscillation of mass m suspended from a spring is 2s, find the period of mass 4m?

17. A vertical U-tube of uniform cross section contains water upto a height of 0.5m. If water on one side is
depressed a little and then released it performs SHM up and down. Calculate (a) time period and (b) angular
frequency of the vibration.

18. At what distance from the mean position is the kinetic energy in simple harmonic oscillation equal to P.E ?

19. A simple pendulum of length l and having a bob of mass m is suspended in a car. The car is moving on a
circular track of radius r with a uniform speed v. If the pendulum makes small oscillations in a radial direction
about its equilibrium position what will be its time period?

20. A mass attached to a spring is free to oscillate, with angular frequency w, in a horizontal plane without friction
or damping. It is pulled to a distance x0 and pushed towards the centre with a velocity v0 at a time t=0. Determine
the amplitude of the resulting oscillations in terms of the parameters w, x0 and v0.

21. What is periodic motion?

22. What is oscillatory motion?

23. Is the damping force constant on a system executing SHM ?

24. Is rotation of earth about its axis is an example of SHM?

25. A body of mass m is suspended by a spring of spring constant k. When the body is depressed a little and
released, find its frequency of oscillation?

26. When displacement is one-fourth of the amplitude, find the fraction of the total energy which is kinetic?

27. A block of mass 5 kg executes simple harmonic motion under the restoring force of a spring. The amplitude
and the time period of the motion are 0.1m and 3.14s respectively. Find the maximum force exerted by the spring
on the block.

28. The total energy of a particle, executing SHM is independent of displacement.

Explain.

29. A uniform cylinder of mass m and radius r is attached to one end of the spring as
shown in the fig on rough horizontal surface. If the cylinder is slightly displaced, then
find the time period of the oscillation given that there is no slipping on the surface.

30. If the length of a simple pendulum is doubled what will be its new time period?

31. In which condition the motion of a simple pendulum is simple harmonic?

 CHAPTER-16 Oscillations
1.

6. What is Simple pendulum? Find an expression for the time period and frequency of a simple pendulum?

7. A simple pendulum is executing Simple harmonic motion with a time T. If the length of the pendulum is
increased by 21 %. Find the increase in its time period?

8. A particle is executing S H M of amplitude 4 cm and T = 4 sec. find the time taken by it to move from positive
extreme position to half of its amplitude?