A 0.03 kg piece of wood is dropped from the top of a 100 m building. At the same time, a 0.02 kg bullet is fired vertically upwards from the ground at 100 m/s and embeds in the wood on impact. What is the time until impact?
उत्तर देखें
सही उत्तर: (C) 1 s
1 अंक · 2023 · सेट A
प्रश्न 52
A machine gun fires 60 bullets per minute at 700 m/s. If each bullet has a mass of 50 g, what power does the machine gun develop?
उत्तर देखें
सही उत्तर: (B) 12250 watt
1 अंक · 2023 · सेट A
प्रश्न 53
A mass m is pushed against a spring of constant k fixed to a wall and rests on a frictionless table. The spring’s natural length is L and is compressed to half its natural length. What is the block’s velocity when the spring reaches its natural length?
उत्तर देखें
सही उत्तर: (B) (L/2)√(k/m)
1 अंक · 2023 · सेट A
प्रश्न 54
How much work is done moving a charge of 5 C across two points with a potential difference of 16 V?
उत्तर देखें
सही उत्तर: (C) 80 J
1 अंक · 2023 · सेट A
प्रश्न 55
You lift a suitcase from the floor and put it on a table. The work you do on it does not depend on
उत्तर देखें
सही उत्तर: (D) More than one of the above
1 अंक · 2023 · सेट A
प्रश्न 56
A rigid body has angular momentum L. If its kinetic energy is halved, what is its angular momentum?
उत्तर देखें
सही उत्तर: (E) None of the above
1 अंक · 2023 · सेट A
प्रश्न 57
A light rod has masses mA and mB attached to its ends. Line XY is perpendicular to the rod, at distances r₁ from mA and r₂ from mB. What is the system’s moment of inertia about XY?
उत्तर देखें
सही उत्तर: (A) mA r₁² + mB r₂²
1 अंक · 2023 · सेट A
प्रश्न 58
When does the moment of inertia of a body come into the picture?
उत्तर देखें
सही उत्तर: (A) When motion is rotational
1 अंक · 2023 · सेट A
प्रश्न 59
Two unequal masses are tied together with a compressed spring. When the chord is burnt, the spring releases them. The masses fly apart with equal
उत्तर देखें
सही उत्तर: (B) Momentum
1 अंक · 2023 · सेट A
प्रश्न 60
Thermal expansion in solids as temperature increases is a consequence of
उत्तर देखें
सही उत्तर: (C) Anharmonicity of lattice vibration
1 अंक · 2023 · सेट A
प्रश्न 61
A steel wire of diameter 0.8 mm and length 1 m is clamped at points 1 m apart. A mass M hung at its midpoint makes it sag by 1 cm. If Y = 2 × 10¹¹ N/m², what is the mass?
उत्तर देखें
सही उत्तर: (A) 82 g
1 अंक · 2023 · सेट A
प्रश्न 62
Inert gases exhibit
उत्तर देखें
सही उत्तर: (B) Diamagnetism
1 अंक · 2023 · सेट A
प्रश्न 63
In the absence of external forces, the shape of a small liquid drop is determined by
उत्तर देखें
सही उत्तर: (B) Surface tension
1 अंक · 2023 · सेट A
प्रश्न 64
What energy is required to move a body of mass m from an orbit of radius 2R to another orbit of radius 3R?
उत्तर देखें
सही उत्तर: (B) GMm/(6R)
1 अंक · 2023 · सेट A
प्रश्न 65
In streamline flow
उत्तर देखें
सही उत्तर: (D) More than one of the above
1 अंक · 2023 · सेट A
प्रश्न 66
If temperature increases, what happens to the modulus of elasticity?
उत्तर देखें
सही उत्तर: (B) Decreases
1 अंक · 2023 · सेट A
प्रश्न 67
When 1 kg of ice melts at 0°C into water at the same temperature, the change in entropy is
उत्तर देखें
सही उत्तर: (C) 293 cal K⁻¹
1 अंक · 2023 · सेट A
प्रश्न 68
A force is exerted at a 30° angle on a cube fixed on a table. What kind of transformation will the cube undergo?
उत्तर देखें
सही उत्तर: (B) Change in both shape and size
1 अंक · 2023 · सेट A
प्रश्न 69
One mole of a perfect gas expands adiabatically, changing P₁, V₁ and T₁ to P₂, V₂ and T₂. If its molar specific heat at constant volume is Cᵥ, the work done by the gas is
उत्तर देखें
सही उत्तर: (B) Cᵥ(T₁ − T₂)
1 अंक · 2023 · सेट A
प्रश्न 70
Which material is unaffected by an applied elastic force?
उत्तर देखें
सही उत्तर: (B) Quartz
1 अंक · 2023 · सेट A
प्रश्न 71
The motion of Halley’s Comet around the Sun is not
उत्तर देखें
सही उत्तर: (D) More than one of the above
1 अंक · 2023 · सेट A
प्रश्न 72
The energy required to raise the temperature of 1 kg of a substance by 1°C is called
उत्तर देखें
सही उत्तर: (B) Specific heat capacity
1 अंक · 2023 · सेट A
प्रश्न 73
On a certain day the air temperature is 20°C and relative humidity is 80%. Saturation vapour pressures at 20°C and 5°C are 17.5 mm Hg and 6.5 mm Hg, respectively. What fraction of the water mass condenses when the temperature falls to 5°C?
उत्तर देखें
सही उत्तर: (B) 0.51
1 अंक · 2023 · सेट A
प्रश्न 74
In an isobaric expansion of a gas
उत्तर देखें
सही उत्तर: (A) Volume and temperature both increase
1 अंक · 2023 · सेट A
प्रश्न 75
A mixture of oxygen and hydrogen is kept at room temperature. Compared with an H₂ molecule, an O₂ molecule hits the container wall with
उत्तर देखें
सही उत्तर: (B) Smaller average speed
1 अंक · 2023 · सेट A
प्रश्न 76
In thermodynamics, which statements are true? (1) Work is path-independent. (2) Work is path-dependent. (3) Work is the area under the curve in a P–V diagram. (4) Work and heat energy are completely interchangeable. Select the correct answer.
उत्तर देखें
सही उत्तर: (C) 2 and 3
1 अंक · 2023 · सेट A
प्रश्न 77
When the temperature of a gas in a rigid container is raised, the pressure on the container wall increases because
उत्तर देखें
सही उत्तर: (C) Molecules have higher average speed and strike the container wall more often
1 अंक · 2023 · सेट A
प्रश्न 78
Which technique cannot be used to generate electron-hole pairs in electronic devices?
उत्तर देखें
सही उत्तर: (C) Impurity injection
1 अंक · 2023 · सेट A
प्रश्न 79
Two periodic waves of amplitudes A₁ and A₂, where A₁ > A₂, pass through a region. What is the difference between the maximum and minimum possible resultant amplitudes?
उत्तर देखें
सही उत्तर: (A) 2A₂
1 अंक · 2023 · सेट A
प्रश्न 80
If the source temperature is increased, the efficiency of a Carnot engine
उत्तर देखें
सही उत्तर: (A) Increases
1 अंक · 2023 · सेट A
प्रश्न 81
Three charges +4q, Q and q are placed in a straight line of length l at distances 0, l/2 and l, respectively. What must Q be to make the net force on q zero?
उत्तर देखें
सही उत्तर: (B) −q
1 अंक · 2023 · सेट A
प्रश्न 82
According to the law of equipartition of energy, the molar specific heat of solids depends on
उत्तर देखें
सही उत्तर: (E) None of the above
1 अंक · 2023 · सेट A
प्रश्न 83
Kirchhoff’s voltage law is satisfied for
उत्तर देखें
सही उत्तर: (D) More than one of the above
1 अंक · 2023 · सेट A
प्रश्न 84
The Vᵣₘₛ of a gas molecule is 300 m/s. If its absolute temperature is halved and its molecular weight doubled, what will Vᵣₘₛ become?
उत्तर देखें
सही उत्तर: (B) 150 m/s
1 अंक · 2023 · सेट A
प्रश्न 85
A copper atom has 29 electrons around its nucleus. Two copper pieces each weigh 10 g. One electron is transferred from one piece to the other for every 1000 atoms. At a separation of 10 cm, what is the Coulomb force? (e = 1.6 × 10⁻¹⁹ C, 1/(4πε₀) = 9 × 10⁹, Avogadro number = 6 × 10²³ per mole, atomic weight of copper = 63.5 g/mol)
उत्तर देखें
सही उत्तर: (A) 2.08 × 10¹⁴ N
1 अंक · 2023 · सेट A
प्रश्न 86
What is the relation between the kinetic energy E of a gas and its pressure P?
उत्तर देखें
सही उत्तर: (A) P = (2/3)E
1 अंक · 2023 · सेट A
प्रश्न 87
A metallic sphere A of radius a is charged to potential V. It is enclosed by a spherical conducting shell B of radius b (b > a) and connected to it by a wire. What is the potential on sphere A?
उत्तर देखें
सही उत्तर: (C) (a/b)V
1 अंक · 2023 · सेट A
प्रश्न 88
What is the phase difference between the prongs of a tuning fork?
उत्तर देखें
सही उत्तर: (B) π
1 अंक · 2023 · सेट A
प्रश्न 89
An electric iron draws 10 A, a toaster 5 A and a refrigerator 3 A from a 220 V line. If all three appliances operate in parallel at the same time, what should the fuse rating be?
उत्तर देखें
सही उत्तर: (B) 20 A
1 अंक · 2023 · सेट A
प्रश्न 90
When a wave is reflected from a denser medium, how does its phase change?
उत्तर देखें
सही उत्तर: (C) π
1 अंक · 2023 · सेट A
प्रश्न 91
An electron moving east is acted on by a magnetic field directed north. The force on the electron is
उत्तर देखें
सही उत्तर: (B) Vertically downward
1 अंक · 2023 · सेट A
प्रश्न 92
A particle undergoes SHM with amplitude 10 cm. What is the minimum acceleration at an extreme point if its maximum speed at the centre is 5 m/s?
उत्तर देखें
सही उत्तर: (C) 250 m/s²
1 अंक · 2023 · सेट A
प्रश्न 93
A capacitor is connected to a 12 V battery through a 10 ohm resistance. The potential difference rises to 4 V in 1 μs. What is the capacitance?
उत्तर देखें
सही उत्तर: (A) 0.25 μF
1 अंक · 2023 · सेट A
प्रश्न 94
A plane progressive wave is y = 25 cos(2πt − πx). What are its amplitude and frequency, respectively?
उत्तर देखें
सही उत्तर: (B) 25, 1
1 अंक · 2023 · सेट A
प्रश्न 95
A ferromagnetic material is placed in an external magnetic field. The magnetic domains
उत्तर देखें
सही उत्तर: (A) Increase in size
1 अंक · 2023 · सेट A
प्रश्न 96
A 4 kg block is attached to a spring with spring constant 400 N/m. Calculate the oscillation period.
उत्तर देखें
सही उत्तर: (A) 0.2π
1 अंक · 2023 · सेट A
प्रश्न 97
If E and B represent the electric and magnetic field vectors in an electromagnetic wave, the direction of propagation is
उत्तर देखें
सही उत्तर: (B) E⃗ × B⃗
1 अंक · 2023 · सेट A
प्रश्न 98
How is the electric field at the surface of a charged conductor related to the surface charge density?
उत्तर देखें
सही उत्तर: (A) Proportional to each other
1 अंक · 2023 · सेट A
प्रश्न 99
An inductor, resistor and capacitor are connected in series to an A.C. source. As the source frequency increases slightly from a very low value, the reactance
उत्तर देखें
सही उत्तर: (A) Of the inductor increases
1 अंक · 2023 · सेट A
प्रश्न 100
What is the order of magnitude of the resistance of a dry human body?