PAPER : CPMT Sample Paper Physics III

1. A wound watch spring
(a) has no energy stored in it
(b) has KE stored in it
(c) has mechanical PE stored in it
(d) has electrical energy stored in it

2. Kirchoff's first law is related to
(a) conservation of energy
(b) conservation of momentum
(c) conservation of angular momentum
(d) conservation of charge

3. The difference between Cp and Cv is equal to the universal gas
constant when
(a) one gram of gas is heated
(b) any amount of gas is heated
(c) one molecule of gas is heated
(d) one gram molecule is heated

4. A wire is drawn so that its radius becomes halved. Its new
resistance
(a) increases to four times (b) decreases to four times
(c) increases to 16 times (d) decreases to 16 times

5. The product of moment of inertia (M.I) and angular acceleration
is
(a) force (b) torque (c) work (d) angular momentum

6. The ratio of angular speeds of seconds hand and minutes hand
of a watch is
(a) 60:1 (b) 1:60 (c) 30:1 (d) 1:30

7. A man moves on a cycle horizontally with a velocity 4 km/hr.
The rain is falling vertically with a velocity 3 km/hr. The direction
in which he should hold the umbrella is
(a) 370 with the vertical (b) 530 with the vertical
(c) vertically (d) 450 with the vertical

8. A particle is thrown upward with a certain initial speed. It
reaches the maximum height and subsequently returns back to
the initial point. Through out its motion, the kinematical quantity
which remains constant is
(a) displacement (b) speed (c) velocity (d) acceleration

9. The order of (2)30 is approximately
(a) 105 (b) 109 (c) 1015 (d) 1020

10. If the momentum of a body is increased by 60% its KE will be
increased by
(a) 50% (b) 100% (c) 125% (d) 156%

11. The excess of pressure inside one soap bubble is three times
that inside a second soap bubble. Their volume are in the ratio
(a) 1:81 (b) 1:27 (c) 1:3 (d) 1:9

12. A wire when connected across a source of emf liberates or
dissipates 60J/s. When it is stretched to double its length, the
heat liberated per second is
(a) 30 J (b) 120 J (c) 15 J (d) 240 J

13. Laplace corrected Newton's formula of velocity of sound
because sound waves in air
(a) Transverse (b) Propagate adiabatically
(c) are longitudinal (d) propagate isothermally

14. In which medium is the speed of sound maximum?
(a) air (b) water (c) iron (d) interstellar space

15. When three bulbs A, B and C in the resistance ratio 1:2:3 are
used separately in a house connection, the brightness is
(a) largest for C (b) largest for B
(c) largest for A (d) same for A, B and C

16. The following is an incorrect statement based on the first law
of thermodynamics
(a) The energy of an isolated system remains constant
(b) The heat transfer equals the work plus the energy change
(c) The heat transfer cannot exceed the work done
(d) The net heat transfer equals the net work done for a cycle

17. Four equal resistances are connected to form a square. The
effective resistance between any two diagonal points is 4Ω.
The resistance of each side is
(a) 4Ω (b) 8Ω (c) 2Ω (d) 16Ω

18. A liquid shows capillary rise. Then its angle of contact is
(a) acute (b) obtuse (c) 900 (d) 00

19. The dimensions of pressure gradient is
(a) ML-2T-2 (b) ML-2T-1 (c) ML-1T-1 (d) ML0T-2

20. Two simple harmonic motions of same amplitude, same
frequency and a phase difference of π results in the
displacement of the particle along a
(a) ellipse (b) circle (c) figure of eight (d) straight line

21. An instrument used for measuring the emf of a cell is
(a) tacho meter (b) ammeter (c) metre bridge (d) volt meter

22. When the area of cross section of a wire is halved and tension
is doubled, the frequency becomes
(a) same (b) two times (c) three times (d) four times

23. The percentage decrease in acceleration due to gravity when a
body is taken to a height 32 km from the surface of the earth
(a) 0% (b) 1% (c) 2% (d) 4%

24. A stone projected with a velocity 100 m/s reaches the highest
point in 5s. The angle of projection is
(a) 00 (b) 300 (c) 450 (d) 600

25. A boy throws an apple vertically up inside a train which is
accelerating along a straight line. The apple
(a) falls behind him
(b) falls ahead him
(c) returns straight to his hands
(d) follows a parabolic path as observed by the boy

26. Two vibrating systems are said to be in resonance if
(a) their amplitudes are equal
(b) their frequencies are equal
(c) their damping factors are equal
(d) their temperatures are the same

27. A mixture of hydrogen and oxygen is taken in a container at
constant temperature. The kinetic energy per molecule is
(a) greater than oxygen (b) greater for hydrogen
(c) same for both the gases (d) zero

28. The best conductor of electric current is
(a) silver (b) copper (c) aluminium (d) nichrome

29. The frequency of transverse vibration of a stretched string is
400 per second. If the tension is increased 4 times, its
frequency will be:
(a) 1600 per second (b) 100 per second
(c) 200 per second (d) 800 per second

30. Two spheres of the same size are made of the same metal, but
one is hollow ad the other is solid. They are heated to the
same temperature:
(a) both spheres will expand equally
(b) the solid sphere will expand more than the hollow one
(c) the solid sphere will expand but the hollow one will not
(d) the hollow sphere will expand more than the solid one

31. A cell is of emf 12 volts and internal resistance 2Ω. When it is
short circuited the current is
(a) zero (b) infinity (c) 12A (d) 6A

32. The weight of a body in air is W. When it floats in water its
weight is
(a) W (b) W/2 (c) zero (d) W/4

33. A spring stretched to a distance x has a PE=U. The additional
energy required to stretch to a distance 2x is
(a) U (b) 2U (c) 3U (d) 4U

34. A person travels along a straight road for the first half length
with a velocity 40 m/s and the second half length with a
velocity 60 m/s. The average velocity is given by
(a) 0 (b) 50 m/s (c) 48 m/s (d) 54 m/s

35. The melting point of substances that contract on melting
(a) decreases with increase in pressure
(b) increases with increase in pressure
(c) decreases at first and then increases with increase in
pressure
(d) is independent of pressure

36. The tension in a sonometer wire is increased four times. The
fundamental frequency becomes
(a) 8 times (b) 2 times (c) 16 times (d) 10 times

37. A river is 120m wide and flows at a speed of 1 m/s. Two
persons A and B can swim at 3 m/s. The approximate difference
in time taken by them to cross the river if A crosses through
shortest path and B in shortest time is
(a) 1 s (b) 2 s (c) 3 s (d) 4 s

38. 27 small liquid drops with radius 1 mm each are combined to
form a single drop. The radius of this large drop is
(a) 1 mm (b) 27 mm (c) 3 mm (d) 1.5 mm

39. A bulb is marked 100 W, 250 V. Then
(a) it always liberates 100J of light
(b) it always draws 0.4 A current
(c) its resistance is 625Ω
(d) all the above are correct

40. The physical quantity which remains unchanged when a sound
wave travels from one medium to another
(a) speed (b) wavelength (c) amplitude (d) frequency

41. Two copper wires have their lengths in the ratio 1:2 and radius
2:1. The ratio between their specific resistances is
(a) 8:1 (b) 4:1 (c) 2:1 (d) 1:1

42. The weight of lead of R.D = 11 which will balance 8gm of iron
of R.D = 8, when both are immersed in water is
(a) 11 gm (b) 8 gm (c) 7.7 gm (d) 8.8 gm

43. The number which has order of magnitude 3 is
(a) 5.01 (b) 5000 (c) 5001 (d) 5.00

44. The weight of an aeroplane in flight is balanced by:
(a) the upthrust of air displaced
(b) difference of pressure between the upper and lower
surfaces of the wings created by he difference of speeds of
air on the surfaces
(c) vertical component of the thrust created by air currents
striking the lower surface of the wings
(d) force due to the reaction of gases ejected by the revolving
propeller

45. A block has dimensions 10×8×4 cm. The ratio between
maximum resistance to minimum resistance formed by the block
is
(a) 5:2 (b) 25:4 (c) 5:4 (d) 1:1

46. Out of the following the one without much variation of
resistance with temperature is
(a) copper (b) silicon (c) constantan (d) nichrome

47. In a stationary wave in air the variation of pressure at nodes is
(a) maximum
(b) minimum
(c) three times the variation due to one wave alone
(d) none of these

48. At Mach number 2, the speed of an aeroplane will be:
(a) half the speed of sound
(b) double the speed of sound
(c) four times the speed of sound
(d) √2 times the speed of sound

49. If the error in measurement of length and time is 2% the
percentage error in velocity is
(a) 1 (b) 2 (c) 4

50. Electrons revolve in a circle with a frequency of 5 × 1014 Hz.
The current due to this is
(a) 5×1014 A (b) 8×10-5A (c) 3.2×10-31 A (d) zero

Answers

1 C 11 B 21 D 31 D 41 D
2 D 12 C 22 B 32 C 42 C
3 D 13 B 23 B 33 C 43 B
4 C 14 C 24 B 34 C 44 B
5 B 15 C 25 A 35 A 45 B
6 A 16 C 26 B 36 B 46 C
7 B 17 A 27 C 37 B 47 A
8 D 18 A 28 A 38 C 48 B
9 B 19 C 29 D 39 C 49 C 10 D 20 A 30 A 40 D 50 B