May, 2022Flame Institute

The weight of an object in the coal mine, sea level, at the top of the mountain are W1,W2 and W3 respectively, then

(a) W1 <W2 > W3 (b) W1 =W2 =W3 (c) W1 < W2 < W3 (d) W1 > W2 >W3 Answer: a (9)

If R is the radius of the earth and g the acceleration due to gravity on the earth’s surface, the mean density of the earth is

a) 4πG/3gR (b) 3πR/4 gG (c) 3g/4πRG (d) …

The radius of the earth is 6400 km and g=10 m/ sec2 . In order that a body of 5 kg weighs zero at the equator, the angular speed of the earth is

(a) 1/80 radian/sec (b) 1/400 radian/sec (c) 1/800 radian/sec (d) 1/1600 radian/sec Answer: c (27)

Force of gravity is least at

(a) The equator (b) The poles (c) A point in between equator and any pole (d) None of these Answer: a (9)

If the earth stops rotating, the value of ‘g’ at the equator will

(a) Increase (b) Remain same (c) Decrease (d) None of the above Answer: a (19)

The mass and diameter of a planet have twice the value of the corresponding parameters of earth. Acceleration due to gravity on the surface of the planet is

(a) 9.8 m/sec2 (b) 4.9 m/sec2 (c) 980 m/sec2 …

As we go from the equator to the poles, the value of g

(a) Remains the same (b) Decreases (c) Increases (d) Decreases upto a latitude of 45° Answer: c (11)

56. On account of melting of ice at the north pole the moment of inertia of spinning earth

(a) Increases (b) Decreases (c) Remains unchanged (d) Depends on the time Ans. a (13)

A spherical planet far out in space has a mass M0 and diameter D0 . A particle of mass m falling freely near the surface of this planet will experience an acceleration due to gravity which is equal to

(a) GM0 /D02 (b) 4m GM0 /D02 (c) 4 GM0 /D02 …

In order to find time, the astronaut orbiting in an earth satellite should use

(a) A pendulum clock (b) A watch having main spring to keep it going (c) Either a pendulum clock or a watch (d) Neither a pendulum clock nor a watch Answer: b (7)

55. Three particles are situated on a light and rigid rod along Y axis as shown in the figure. If the system is rotating with an angular velocity 2 rad/s of about X axis, then the total kinetic energy of the system is

(a) 92 J (b) 184 J (c) 276 J (d) 46 J Ans. b (52)

A body weighs 700 gm wt on the surface of the earth. How much will it weigh on the surface of a planet whose mass is 1/7 and radius is half that of the earth

(a) 200 gm wt (b) 400 gm wt (c) 50 gm wt (d) 300 gm wt Answer: b (14)

A body of mass m is taken to the bottom of a deep mine. Then

(a) Its mass increases (b) Its mass decreases (c) Its weight increases (d) Its weight decreases Answer: d (24)

When a body is taken from the equator to the poles, its weight

(a) Remains constant (b) Increases (c) Decreases (d) Increases at N-pole and decreases at S-pole Answer: b (9)

The correct answer to above question is based on

(a) Acceleration due to gravity in vacuum is same irrespective of size and mass of the body (b) Acceleration due to gravity in vacuum depends on the mass of the body (c) There is no acceleration due to gravity in …

An iron ball and a wooden ball of the same radius are released from a height ‘h’ in vacuum. The time taken by both of them to reach the ground is

(a) Unequal (b) Exactly equal (c) Roughly equal (d) Zero Answer: b (16)

Two planets have the same average density but their radii are R1 and R2 . If acceleration due to gravity on these planets be g1 and g2 respectively, then

(a) g1/g2 = R1/R2 (b) g1/g2 = R2/R1 (c) g1/g2 = R12/R22 …

The time period of a simple pendulum on a freely moving artificial satellite is

(a) Zero (b) 2 sec (c) 3 sec (d) Infinite Answer: d (15)

If the change in the value of ‘g’ at a height h above the surface of the earth is the same as at a depth x below it, then (both x and h being much smaller than the radius of the earth)

(a) x=h (b) x=2h (c) x=h/2 …

Weightlessness experienced while orbiting the earth in space-ship, is the result of

(a) Inertia (b) Acceleration (c) Zero gravity (d) Free fall towards earth Answer: d (20)

Two identical solid copper spheres of radius R placed in contact with each other. The gravitational attracton between them is proportional to

(a) R2 (b) R–2 (c) R4 (d) R–4 Answer: c (17)

Which of the following statements about the gravitational constant is true

(a) It is a force (b) It has no unit (c) It has same value in all systems of units (d) It depends on the value of the masses (e) It does not depend on the nature of the …

Earth binds the atmosphere because of

(a) Gravity (b) Oxygen between earth and atmosphere (c) Both (a) and (b) (d) None of these Answer: a (12)

Two sphere of mass m and M are situated in air and the gravitational force between them is F. The space around the masses is now filled with a liquid of specific gravity 3. The gravitational force will now be

(a) F (b) F/3 (c) F/9 …

The gravitational force Fg between two objects does not depend on

(a) Sum of the masses (b) Product of the masses (c) Gravitational constant (d) Distance between the masses Answer: a (23)

The force of gravitation is

(a) Repulsive (b) Electrostatic (c) Conservative (d) Non-conservative Answer: c (7)

54. Moment of inertia of a sphere of mass M and radius R is I. Keeping constant if a graph is plotted between I and R, then its form would be

Ans. d (21)

Mass M is divided into two parts xM and (1-x) M . For a given separation, the value of x for which the gravitational attraction between the two pieces becomes maximum is

(a) 1/2 (b) 3/5 (c) 1 …

Two loops P and Q are made from a uniform wire. The radii of P and Q are r1 and r2 respectively, and their moments of inertia are l1 and l2 respectively. If l2/l1=4 then r2/r1 equals

(a) 42/3 (b) 41/3 (c) 4-2/3 (d) 4-1/3 Ans. b (18)

53. Three identical thin rods each of length l and mass M are joined together to form a letter H. What is the moment of inertia of the system about one of the sides of H

(a) Ml2/3 (b) Ml2/4 (c) 2Ml2/3 (d) 4Ml2/3 Ans. d (8)

Reason of weightlessness in a satellite is

(a) Zero gravity (b) Centre of mass (c) Zero reaction force by satellite surface (d) None Answer: c (13)

Who among the following gave first the experimental value of G

(a) Cavendish (b) Copernicus (c) Brook Teylor (d) None of these Answer: a (13)

The moment of inertia of a sphere (mass M and radius R) about it’s diameter is I. Four such spheres are arranged as shown in the figure. The moment of inertia of the system about axis xx’ will be

(a) 3I (b) 5 I (c) 7 I (d) 9 I Ans. d (16)

The centripetal force acting on a satellite orbiting round the earth and the gravitational force of earth acting on the satellite both equal F. The net force on the satellite is

(a) Zero (b) F (c) F √2 (d) 2 Fb Answer: b (16)

The mass of the moon is 7.34×1022 kg and the radius is 1.74×106 m . The value of gravitation force will be

(a) 1.45 N/kg (b) 1.55 N/kg (c) 1.75 N/kg (d) 1.62 N/kg Answer: d (13)

The distance of the centres of moon and earth is D. The mass of earth is 81 times the mass of the moon. At what distance from the centre of the earth, the gravitational force will be zero

(a) D/2 (b) 2D/3 (c) 2D/4 …

50. In a rectangle ABCD (BC=2AB) . The moment of inertia along which axis will be minimum

(a) BC (b) BD (c) HF (d) EG Ans. d (36)

49. Three point masses m1, m2, m3 are located at the vertices of an equilateral triangle of length ‘a’ . The moment of inertia of the system about an axis along the altitude of the triangle passing through m1 is

(a) (m2+m3)a4/4 (b) (m 1+m2+m 3)a2 (c) (m1+m2)a2/2 (d) (m2+m3)a2 Ans. a (46)

The gravitational force between two point masses m1 and m2 at separation r is given by F = k m1 m2/r2 The constant k

(a) Depends on system of units only (b) Depends on medium between masses only (c) Depends on both (a) and (b) (d) Is independent of both (a) and (b) Answer: a (52)

Gravitational mass is proportional to gravitational

(a) Field (b) Force (c) Intensity (d) All of these Answer: d (14)

Month: May 2022

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