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A hydraulic press can lift 100 kg when a mass ‘m’ is placed on the smaller piston. It can lift _______ kg when the diameter of the larger piston is increased by 4 times and that of the smaller piston is decreased by 4 times keeping the same mass ‘m’ on the smaller piston.

Answer: 25600 Atmospheric pressure P0 will be acting on both the limbs of the hydraulic lift. Applying pascal’s law for the same liquid... View Article

An electromagnetic wave of frequency 5 GHz, is travelling in a medium whose relative electric permittivity and relative magnetic permeability both are 2. Its velocity in this medium is _______ × 10⁷ m/s.

Answer: 15 Given: f = 5 GHz εr =2 μr = 2 Velocity of wave ⇒ v = c / n ....(1) Where, n = √μrεr and c =... View Article

An inclined plane is bent in such a way that the vertical cross-section is given by y = x² / 4 where y is in vertical and x in horizontal direction. If the upper surface of this curved plane is rough with a coefficient of friction μ = 0.5, the maximum height in cm at which a stationary block will not slip downward is _____ cm.

Answer: 25 Given, y = x2 / 4 μ = 0.5 Condition for block will not slip downward mg sin θ = μmg cos θ ⇒ tan... View Article

The coefficient of static friction between a wooden block of mass 0.5 kg and a vertical rough wall is 0.2. The magnitude of horizontal force that should be applied on the block to keep it adhere to the wall will be ______ N. [g = 10 ms^-2]

Answer: 25 Given: μs = 0.2 m = 0.5 kg g = 10 m/s2 We know that fs = μsN and .... (1) To keep the block adhere to the wall Here, N... View Article

An audio signal υ_m = 20sin2π(1500t) amplitude modulates a carrier υ_c =80 sin 2π (100,000t). The value of percent modulation is ________.

Answer: 25 We know that, modulation index = Am / Ac From given equations, Am = 20 and Ac = 80 Percentage modulation index = Am / Ac ×... View Article

A ball with a speed of 9 m/s collides with another identical ball at rest. After the collision, the direction of each ball makes an angle of 30° with the original direction. The ratio of velocities of the balls after collision is x : y, where x is _________.

Answer: 1 Momentum is conserved just before and just after the collision in both x-y direction. In y-direction, pi = 0 pf = mv1 sin30o... View Article

A resonance circuit having inductance and resistance 2 × 10^–4 H and 6.28 Ω respectively oscillates at 10 MHz frequency. The value of the quality factor of this resonator is________. [π = 3.14]

Answer: 2000 Given: R = 6.28 Ω f = 10 MHz L = 2 × 10-4 Henry We know that quality factor Q is given by ⇒ Q = XL / R =... View Article

Each side of a box made of metal sheet in cubic shape is ‘a’ at room temperature ‘T’, the coefficient of linear expansion of the metal sheet is ‘α’. The metal sheet is heated uniformly, by a small temperature ΔT, so that its new temperature is T+ΔT. Calculate the increase in the volume of the metal box:

a. 4/3 πa3αΔT b. 4πa3αΔT c. 3a3αΔT d. 4a3αΔT Answer: (c) Coefficient of volumetric... View Article

A cube of side ‘a’ has point charges +Q located at each of its vertices except at the origin where the charge is –Q. The electric field at the centre of cube is:

Answer: (c) We can replace –Q charge at origin by +Q and –2Q. Now due to +Q charge at every corner of the cube, the electric... View Article

03 Aug 2021: UPSC Exam Comprehensive News Analysis

August 3rd, 2021, PIB:- Download PDF Here TABLE OF CONTENTS A. GS 1 Related B. GS 2 Related POLITY AND GOVERNANCE 1. Amid protests, LS passes... View Article

02 Aug 2021: PIB Summary & Analysis

TABLE OF CONTENTS 1. e-RUPI 2. 12th Round of India-China Corps Commander Level Meeting 3. MSMEs Day 4. Pradhan Mantri Jan Vikas Karyakaram... View Article

The mass of the moon is about 1.2% of the mass of the earth. Compared to the gravitational force the earth exerts on the moon, the gravitational force the moon exerts on the earth

1) is the same 2) is smaller 3) is greater 4) varies with its phase Answer: 1) is the same Solution: The gravitational force of attraction... View Article

For a body to escape from earth, angle at which it should be fired is

1) 45o 2) > 45o 3) < 45o and 4) any angle Answer: 4) any angle Solution: The particle has to be fired with escape velocity,... View Article

If one moves from the surface of earth to moon, what will be the effect on its weight?

1) Weight of a person decreases continuously with height from the surface of earth 2) Weight of a person increases with height from the surface... View Article

Gravitational attraction on Earth on the stone of mass M is F_S. If the force on the hydrogen balloon of mass M located at the same space is F_B, then

1) FS > FB 2) FS < FB 3) FS = FB 4) FS = -FB Answer: 3) FS = FB Solution: Since mass M of the bodies is same, so gravitational... View Article

What is a period of revolution of the earth satellite? Ignore the height of satellite above the surface of the earth. Given, the value of gravitational acceleration g = 10 ms ^-2, radius of the earth Re = 6400 km. (take, π = 3.14)

1) 85 min 2) 156 min 3) 83.73 min 4) 90 min Answer: 3) 83.73 min Solution: Radius of earth RE = 6400 km = 6.4 x 106 m Time period of... View Article

There are two planets. The ratio of radius of the two planets is K but ratio of acceleration due to gravity of both planets is g. What will be the ratio of their escape velocity?

1) ( kg ) 1/2 2) ( kg ) -1/2 3) ( kg ) 2 4) ( kg ) -2 Answer: 1) ( kg ) 1/2 Solution: Escape velocity, --------(1) Acceleration due to... View Article

Weight of a body of mass m decreases by 1% when it is raised to height h above the earth’s surface. If the body is taken to a depth h in a mine, change in its weight is

1) 0.5% decrease 2) 2% decrease 3) 0.5% increase 4) 1% increase Answer: 1) 0.5% decrease Solution: Weight = mg g = GM/r2 gh = Gm/(r +... View Article

A geostationary satellite is revolving around the earth. To make it escape from gravitational field of earth, its velocity must be increased

1) 100 % 2) 41.4 % 3) 50 % 4) 59.6 % Answer: 2) 41.4 % Solution: ⇒ Centripetal force on satellite = Gravitional force between satellite... View Article

The period of a planet around sun is 27 times that of the earth. The ratio of radius of planet’s orbit to the radius of the earth’s orbit is

1) 4 2) 9 3) 64 4) 27 Answer: 2) 9 Solution: Kepler's third law of motion (Te2/Tp2) = (Re3/Rp3) Given, Tp = 27 Te (Te2/272 Te2) =... View Article

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