A spring is cut into two equal halves. The spring constant of each half will be
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Correct answer: (B) twice that of the original spring
1 marks · 2023 · Set A
Question 102
If the momentum of a body increased by 300%, then the percentage increase in momentum would be
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Correct answer: (A) 300%
1 marks · 2023 · Set A
Question 103
An electron and a proton are detected in a cosmic-ray experiment, the first with kinetic energy 10 keV and the second with 100 keV. How are their velocities related?
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Correct answer: (B) Electron moving faster
1 marks · 2023 · Set A
Question 104
The casing of a rocket in its flight from Earth to the Moon burns due to friction. The heat energy required for burning comes from
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Correct answer: (A) rocket
1 marks · 2023 · Set A
Question 105
A comet moves around the Sun in an elliptical orbit. The work done by the Sun’s gravitational force over every complete orbit of the comet would be
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Correct answer: (C) zero
1 marks · 2023 · Set A
Question 106
A helicopter lifts an astronaut of mass 72 kg vertically 15 metres from the ocean by means of a cable. If the acceleration acting on the astronaut is g/10, the work done by the helicopter would be
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Correct answer: (A) 11880 joules
1 marks · 2023 · Set A
Question 107
A boy of mass 40 kg walks up a flight of stairs to a vertical distance of 12 metres in 40 seconds. The rate of doing work against gravity, with g = 10, would be
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Correct answer: (A) 120 watt
1 marks · 2023 · Set A
Question 108
In an elastic collision between two bodies of equal mass, kinetic energy is conserved
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Correct answer: (A) after the collision
1 marks · 2023 · Set A
Question 109
A railway carriage of mass 8000 kg moving at 54 km/hour collides with another stationary carriage of the same mass. The loss of kinetic energy would be
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Correct answer: (A) 450 kilojoules
1 marks · 2023 · Set A
Question 110
The power of a motor capable of raising 2000 litres of water from a well 120 metres deep in 5 minutes would be (g = 9.8; density of water = 1 kg/litre)
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Correct answer: (A) 7.840 kW
1 marks · 2023 · Set A
Question 111
A pump on the ground floor of a building can pump water to fill a tank of volume 30 m³ in 15 minutes. If the tank is 40 metres above the ground and the pump efficiency is 30%, the electric power consumed is
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Correct answer: (A) 43.57 kW
1 marks · 2023 · Set A
Question 112
In an atom, an electron revolves in a circular orbit of radius 0.53 Å with a velocity of 2.2 × 10⁶ m/s at an angle of 30°. If the mass of the electron is 9 × 10⁻³¹ kg, its angular momentum would be
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Correct answer: (E) None of the above
1 marks · 2023 · Set A
Question 113
If the linear and angular momentum of a rigid body are not changing with time, the body is said to be in
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Correct answer: (A) equilibrium
1 marks · 2023 · Set A
Question 114
The bottom of a ship is made heavy to keep its centre of gravity
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Correct answer: (A) at low level
1 marks · 2023 · Set A
Question 115
A particle on a rotating disc has initial and final angular positions: (i) −2 rad, +6 rad; (ii) −4 rad, −8 rad; (iii) +6 rad, +2 rad. In which case does the particle undergo a negative displacement?
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Correct answer: (D) More than one of the above
1 marks · 2023 · Set A
Question 116
The moment of inertia I of a rigid body about an axis of rotation and its rotational kinetic energy (KE) when rotating with unit angular velocity about that axis are related as
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Correct answer: (A) I = 2KE
1 marks · 2023 · Set A
Question 117
An energy of 484 joules is spent in increasing the speed of a flywheel from 60 r.p.m. to 360 r.p.m. The moment of inertia of the flywheel would be
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Correct answer: (A) 0.7 kg·m²
1 marks · 2023 · Set A
Question 118
The angular speed of a motor wheel increases from 1200 r.p.m. to 3120 r.p.m. in 16 seconds. Its uniform angular acceleration would be
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Correct answer: (A) 4π rad/s²
1 marks · 2023 · Set A
Question 119
A wheel has a constant angular acceleration of 3.0 rad/s². During a 4.0-second interval, it turns through an angle of 120 rad. Its initial angular speed at t = 0 would be
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Correct answer: (B) 24 rad/s
1 marks · 2023 · Set A
Question 120
The maximum and minimum distances of a comet from the Sun are 1.4 × 10¹² metres and 7 × 10¹⁰ metres. If its speed nearest the Sun is 6 × 10⁴ m/s, its speed farthest from the Sun would be
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Correct answer: (A) 3000 m/s
1 marks · 2023 · Set A
Question 121
A mass M is broken into two parts, m and M − m. How are m and M related so that the gravitational force between the two parts is maximum?
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Correct answer: (A) m = M/2
1 marks · 2023 · Set A
Question 122
A Saturn year is 29.5 times the Earth year. How far is Saturn from the Sun when the Earth is 1.5 × 10⁸ km from the Sun?
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Correct answer: (A) 14.3 × 10⁸ km
1 marks · 2023 · Set A
Question 123
Pascal’s law to calculate the pressure exerted by a liquid is applicable when the fluid is
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Correct answer: (A) static
1 marks · 2023 · Set A
Question 124
The equation giving the relation among temperatures measured on the Centigrade, Fahrenheit and Reaumur scales can be written as
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Correct answer: (A) C/100 = (F − 32)/180 = R/80
1 marks · 2023 · Set A
Question 125
An average induced e.m.f. of 0.2 V appears in a coil when the current in it is changed from 5.0 A in one direction to 5.0 A in the opposite direction in 0.2 s. The self-inductance of the coil is
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Correct answer: (A) 4.0 mH
1 marks · 2023 · Set A
Question 126
A glass block has volume 15000 cm³. On heating from 20°C to 45°C, its volume increases by 5 cm³. The linear expansion coefficient would be
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Correct answer: (A) 4.4 × 10⁻⁶ °C⁻¹
1 marks · 2023 · Set A
Question 127
The temperature of water at the top of a waterfall and at its bottom remains
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Correct answer: (B) different
1 marks · 2023 · Set A
Question 128
When a thermodynamic system undergoes a physical change at constant pressure, the thermodynamic process is called
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Correct answer: (A) isobaric process
1 marks · 2023 · Set A
Question 129
70 calories of heat is required to raise the temperature of 2 mol of an ideal gas at constant pressure from 30°C to 35°C. If R = 2 cal/mol-K, the increase in internal energy of the gas would be
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Correct answer: (B) 50 calories
1 marks · 2023 · Set A
Question 130
A process in which, after interchange of heat and work, the system is restored to its initial state is known as
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Correct answer: (B) cyclic process
1 marks · 2023 · Set A
Question 131
When air quickly leaks out of a balloon, it becomes
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Correct answer: (B) cool
1 marks · 2023 · Set A
Question 132
The first law of thermodynamics, ΔQ = ΔU + ΔW, for an isothermal expansion of an ideal gas becomes
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Correct answer: (A) ΔQ = ΔW
1 marks · 2023 · Set A
Question 133
During driving a car, the air pressure in the car tyres
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Correct answer: (B) increases
1 marks · 2023 · Set A
Question 134
The volume of a given mass of gas at 27°C and 1 atmosphere pressure is 100 cc. Its volume at 327°C would be
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Correct answer: (A) 200 cc
1 marks · 2023 · Set A
Question 135
The average distance travelled by a molecule between two successive collisions is known as
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Correct answer: (A) mean free path
1 marks · 2023 · Set A
Question 136
Eight dipoles of magnitude ±e are placed inside a cube. What will be the total flux coming out of the cube?
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Correct answer: (A) Zero
1 marks · 2023 · Set A
Question 137
A semicircular arc of radius a is charged uniformly with charge per unit length λ. The electric field at the centre would be
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Correct answer: (E) None of the above
1 marks · 2023 · Set A
Question 138
Two point charges separated by a distance d repel each other with a force of 9 N. If their separation becomes 3d, the force of repulsion will be
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Correct answer: (A) 1 N
1 marks · 2023 · Set A
Question 139
The net charge on a current-carrying conductor remains
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Correct answer: (C) zero
1 marks · 2023 · Set A
Question 140
A gang condenser is formed by interlocking several plates as shown. The distance between consecutive plates is 0.885 cm and the overlapping area of the plates is 5 cm². The capacitance of the unit is (ε₀ = 8.85 × 10⁻¹²).
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Correct answer: (A) 1.06 pF
1 marks · 2023 · Set A
Question 141
The equivalent capacitance in the figure shown would be
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Correct answer: (B) 2ε₀A/d
1 marks · 2023 · Set A
Question 142
The equivalent resistance between points A and B of the circuit shown would be
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Correct answer: (B) R/2 Ω
1 marks · 2023 · Set A
Question 143
Which factor is immaterial for the wire used in an electric fuse?
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Correct answer: (A) Length
1 marks · 2023 · Set A
Question 144
Find the resistance between points A and B situated on the circle of diameter AB, 2 metres, shown in the figure. Both semicircles and the diameter are made of uniform wire of resistance 1 × 10⁻⁴ Ω m⁻¹.
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Correct answer: (C) 0.88 × 10⁻⁴ Ω
1 marks · 2023 · Set A
Question 145
Two parallel wires in free space are 10 cm apart, and each carries a current of 10 amperes in the same direction. The force one wire exerts on the other per metre of length is
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Correct answer: (A) 2 × 10⁻⁴ N attractive
1 marks · 2023 · Set A
Question 146
A motor generates a 210 V back e.m.f. when the applied voltage is 240 V and armature current is 50 A. The power dissipated in the motor is
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Correct answer: (E) None of the above
1 marks · 2023 · Set A
Question 147
In a series L-C-R circuit, the potential difference across the inductor is 60 V, across the capacitor 30 V, and across the resistor 40 V. The supply voltage would be
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Correct answer: (C) 50 volts
1 marks · 2023 · Set A
Question 148
A transformer has an efficiency of 80%. It works at 4 kW and 100 V. If the secondary voltage is 240 V, the current in the primary coil would be
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Correct answer: (C) 40 amperes
1 marks · 2023 · Set A
Question 149
The photoelectric threshold frequency of a metal is γ. When light of frequency 4γ is incident on the metal, the maximum kinetic energy of the emitted photoelectron will be
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Correct answer: (B) 3hγ
1 marks · 2023 · Set A
Question 150
An electron and a proton possess the same kinetic energy. Their de Broglie wavelengths will be