MAHARISHI VIDYA MANDIR SENIOR SECONDARY SCHOOL

CHETPET, CHENNAI-31
PRE - ANNUAL EXAMINATION (2022-2023)
PHYSICS – 042/I
CLASS: XI MAX.MARKS: 70
DATE: 04-02-2023 TIME: 3 HOURS
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General Instructions:
1. There are 35 questions in all. All questions are compulsory.
2. This question paper has five sections: Section A, Section B, Section C, Section D and
Section E. All the sections are compulsory.
3. Section A contains eighteen MCQ of 1 mark each, Section B contains seven questions
of two marks each, Section C contains five questions of three marks each, section D
contains three long questions of five marks each and Section E contains two case study
based questions of 4 marks each.
4. There is no overall choice. However, an internal choice has been provided in section
A, B, C, D and E. You have to attempt only one of the choices in such questions.

SECTION – A 1 x 18 = 18

Choose the correct option in the following questions

1. The unit of “impulse per unit area” is same as that of

a) Viscosity b) Surface tension c) Bulk modulus d) Force

2. The dimensions of potential energy of an object in mass, length and time are
respectively

a) [M2L2T1] b) [M1L2T-2] c) [M-2L1T2] d) [M1L-1T2]

3. Two bodies are thrown vertically upwards with their initial speeds in the ratio 2:3.
Then the ratio of the maximum heights attained by them is

a) 2 : 3 b) 1 : 1 c) 5 : 6 d) 4 : 9
Or
A stone is dropped from a balloon moving upwards at 20 m/s at a height of
105 m. Distance travelled by the stone, just before reaching the ground is

a) 125m b) 120 m c) 130 m d) 145 m

4. If you quadruple the orbital speed v and half the angular velocity ω of a revolving
body, what happens to the centripetal acceleration?
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a) The centripetal acceleration is halved.

b) The centripetal acceleration is doubled.
c) The centripetal acceleration is quadrupled.
d) The centripetal acceleration remains unchanged.
5. Find the value of x from the given diagram. [g = 10 m/s2]

a) 500 m b) 200 m c) 600 m d) 300 m

6. Convert 303 K temperature into Fahrenheit scale.

a) 86 F b) 80 F c) 50 F d) 60 F
7. The number of degrees of freedom for linear molecule of triatomic gas is

a) 3 b) 5 c) 9 d) 7
8. Boyle’s law is applicable in
a) Isochoric process c) Isothermal process
b) Isobaric process d) Adiabatic process

9. The fracture point in the following graph is

a) P b) Q c) R d) S
10. The lift of an aeroplane is based on

a) Bernoulli’s principle c) Torricelli’s principle

b) Law of gravitation d) Coulomb’s law
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11. A particle moves along the x-axis from x = 0 to x = 5 m under the effect of a
force given by F = (7 - 2x + 3x2) N. Work done by this force in joule is
a) 70 b) 270 c) 35 d) 135
12. The internal energy of an ideal gas depends upon

a) Specific volume b) density c) Pressure d) Temperature

13. A body is projected vertically upwards with a velocity u. It crosses a point in its journey
at a height (h) meter twice, just after 1 and 7 seconds .The value
of u in ms−1 is (g=10ms−2)
a) 50 b) 20 c) 40 d) 30

14. The frequency of the note produced by plucking a given string increases as

a) The length of the string increases c) The tension in the string increases
b) The tension in the string decreases d) The mass per unit length increases

Or

Energy is to be carried from one place to another. Which one of the following
cannot be used?

a) Longitudinal progressive waves c) Transverse progressive waves

b) Electromagnetic waves d) Stationary waves

15. Loudness of a note of sound is

a) Directly proportional to amplitude of the wave

b) Directly proportional to square of amplitude of wave
c) Directly proportional to velocity of the wave
d) Directly proportional to square of velocity of the wave

In the following questions, a statement of Assertion (A) is followed by a

statement of Reason (R). Choose the correct answer out of the following
choices.
a) Both A and R are true and R is the correct explanation of A.
b) Both A and R are true but R is not the correct explanation of A.
c) A is true but R is false.
d) A is false and R is also false.

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 16) Assertion (A) : The periodic time of a hard spring is less as compared to that
of a soft spring.
Reason (R) : The periodic time is dependent upon the spring constant, and
spring constant is large for hard spring.
17) Assertion (A) : Distance and displacement are two different physical
quantities.
Reason (R) : Distance and displacement both have the same dimension.
18) Assertion (A): A spring has potential energy when it is compressed or
stretched.
Reason (R) : On compressing or stretching a string, work is done on the
spring against the restoring force which is conservative in
nature.
SECTION – B 2 x 7 =14

A = 2 ⃗i +3 ⃗j+ 4 ⃗k and
19. Find the dot product of the given two vectors by⃗
B = 9 i⃗ +9 ⃗j+9 k⃗
⃗

20. An object is moving vertically up with constant velocity.

Match the two columns

Column I Column II

(i) Work done by gravity (p) zero

(ii) Work done by lifting force (q) negative

(iii) Total work done by all the forces (r) positive

(iv) Work done by lifting force + work done by gravity (s) infinite

21. In Fig.(i) the man walks 2 m carrying a mass of 15 kg in his hands. In Fig. (ii),
he walks the same distance pulling the rope behind him. The rope goes over a
pulley, and a mass of 15 kg hangs at its other end. In which case is the work done
greater?

042/I/5
22. Obtain an expression showing the variation of acceleration due to gravity with
height.

23. When the pressure on a sphere is increased by 80 atmospheres. Then its volume
decreases by 0.01%. Find the bulk modulus of elasticity of the material of sphere.

Or

A structural steel rod has a radius of 10mm and a length of 1m. A 100kN force F
stretches it along its length. Calculate stress and elongation. Given Young’s
modulus Y of the structural steel is 2 X 1011 N/m2

24. Define the term gravitational potential. State its nature? Give the units and
dimensions of gravitational potential.

25. What type of mechanical waves will expect to exist in a) vacuum b) air

c) rock d) on the surface of water

Or

Give two difference between Progressive and Stationary waves.

SECTION - C 3 x 5 = 15

26. A cyclist move along a circular path of radius 70m. If he completes one round in 11s,
calculate (i) total length of path, (ii) magnitude of the displacement, and (iii) average
speed Or
A constant force acting on a body of mass 3kg changes its speed from 2m/s to 3.5 m/s
in 25s. The direction of motion of the force remains unchanged. What is the magnitude
and direction of the force?
27. Derive a relation between the co-efficient of linear expansion and the co–efficient of
cubical expansion.

042/I/6
28. An object of mass 0.4kg moving with a velocity of 4m/s collides with another object
of mass 0.6kg moving in the same direction with a velocity of 2m/s. If the collision is
perfectly inelastic, what is the loss of K.E. due to impact?
Or
Four particles of mass 1kg, 2kg, 3kg and 4kg are placed at the four vertices A , B , C
and D of square of side 1m . Find the position of centre of mass of the particle.
29. i) State the Hooke’s law.
ii) A steel wire of length 4m and diameter 5mm is stretched by 5kg-wt. Find the
increase in its length. If the young’s modulus of steel wire is 2.14X10 12 dyne/cm2

30.Show that terminal velocity of a spherical object of radius(r), density(ρ) falling

vertically through a viscous fluid of density(σ) and coefficient of viscosity( ղ ) is given by
2
2 ( ρ−σ ) r g
v= 9ղ

SECTION - D 5 x 3 = 15

31. On the basis of kinetic theory, derive an expression for the pressure exerted by an
ideal gas Or

Derive an expression for the work done in an isothermal process

32. (i) Derive expression for kinetic energy and potential energies of simple harmonic
oscillator. Hence show that the total energy is conserved.

(ii) What is the length of a simple pendulum which ticks second?

Or

Describe the various modes of vibrations of an open organ pipe.

33. A projectile is fired with a velocity u making an angle θ with the horizontal. Show
that its trajectory is a parabola. Derive expressions for (i) time of maximum height (ii)
time of flight (iii) maximum height (iv) horizontal range.

Or

(i) Two masses M and m are connected at the two ends of an inextensible string. The
string passes over a smooth frictionless pulley. Calculate the acceleration of the
masses and the tension in the string. Given M>m.
(ii) A body rolled on ice with a velocity of 8m/s comes to rest after travelling 4m.
compute the coefficient of friction. Given g – 9.8m/s2.

042/I/7

SECTION - E 2X4=8
34. CASE STUDY

The property of a body, by virtue of which it tends to regain its original size and shape
when the applied force is removed, is known as elasticity and the deformation caused is
known as elastic deformation. However, if you apply force to a lump of putty or mud,
they have no gross tendency to regain their previous shape, and they get permanently
deformed. Such substances are called plastic and this property is called plasticity. Putty
and mud are close to ideal plastics. We know that in a solid, each atom or molecule is
surrounded by neighbouring atoms or molecules. These are bonded together by
interatomic or intermolecular forces and stay in a stable equilibrium position. When a
solid is deformed, the atoms or molecules are displaced from their equilibrium positions
causing a change in the interatomic (or intermolecular) distances. When the deforming
force is removed, the interatomic forces tend to drive them back to their original
positions. Thus the body regains its original shape and size.

(i) The ability of the material to deform without breaking is called

a) Elasticity b) Plasticity c) creep d) None of these

(ii) Glass, Rubber, Steel and Copper arrange in order of increasing the property of

elasticity
(iii) What is the ratio of lateral strain to longitudinal strain is called?
(iv) Why steel is more elastic than rubber?
35. The gravitational potential energy of an object at a point above the ground is defined
as the work done in raising it from the ground by height h to that point against gravity.
Let the work done on the object against gravity be W. That is, work done,

W = force × displacement = mg × h

Therefore potential energy (PE) = mg*h. The dimensions of potential energy are [ML 2T-2]
and the unit is joule (J), the same as kinetic energy or work. To reiterate, the change in
potential energy, for a conservative force, ΔV is equal to the negative of the work done
by the force ΔV = − F(x) Δx.

Conservation of mechanical energy: Suppose that a body undergoes displacement

Δx under the action of a conservative force F. Then from the WE theorem we have, ΔK =
F(x) Δx. If the force is conservative, the potential energy function V(x) can be defined
such that − ΔV = F(x) Δx. The equations imply that ΔK + ΔV = 0 or Δ (K + V) = 0.

042/I/8

Which means that K + V, the sum of the kinetic and potential energies of the body is a
constant? Over the whole path, xi to xf, this means that Ki + V(xi ) = Kf + V(xf ). The
quantity K +V(x), is called the total mechanical energy of the system. Individually the
kinetic energy K and the potential energy V(x) may vary from point to point, but the
sum is a constant. The aptness of the term ‘conservative force’ is now clear.

Let us consider some of the definitions of a conservative force.

A force F(x) is conservative if it can be derived from a scalar quantity V(x).

 The work done by the conservative force depends only on the end points. This can

be seen from the relation, W = Kf – Ki = V (xi ) – V(xf ) which depends on the end
points.

A third definition states that the work done by this force in a closed path is zero.
This is once again apparent since xi = xf .

Thus, the principle of conservation of total mechanical energy can be stated as the total
mechanical energy of a system is conserved if the forces, doing work on it, are
conservative.

(i) What is the formula for gravitational potential energy?

(ii) Find the gravitational potential energy of 2.5kg mass kept at a height of 15m above
the ground. The force of gravity on mass 1kg is 10N.

(iii) State conservation of mechanical energy

(iv) Which of the following has same unit?

a) Potential energy and work b) Kinetic energy and work c) Force and weight d) All of the above

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