Gravitation

Gravitation

If the distance between two masses is halved the gravitational force is:

a) Halved b) Doubled c) 4 Times d) None

Newton’s law of Gravitation states that the force of attraction between the two bodies is inversely proportional to:

a) Product of their masses b) Square of the distance between them

c) Square of the distance between their centers d) Product of mass & distance between them


The gravitational force between two bodies is:

a) Impulsive b) Reactive

c) Repulsive d) Attractive


Newton’s law of Gravitation states that the force of attraction between two bodies is directly proportional to:

a) Product of mass and distance between them b) Square of the distance between them

c) Product of their masses d) Product of square of their masses


Which force is responsible for the motion of falling bodies and the motion of planets around the sun?

a) Nuclear force b) Gravitational force

c) Electrostatic force d) Electromagnetic force


If law of gravitation is written in vector form with negative sign, then gravitational force is written as

a) Attractive force b) Repulsive force

c) Negative force d) None of these


Mass per unit volume is called:

a) Torque b) Density

c) Viscosity d) None of these


The mean density of earth is:

a) 5462 kgm-3 b) 5462 gm-3

c) 5462 kgm3 d) None of these


The radius of earth is:

a) 6400 m b) 6400 km

c) 6400 cm d) 6400 dm


It is a measure of its reluctance to change its state of motion when force is applied:

a) Mass b) Inertial mass

c) Gravitational mass d) None of the above


When a body is lifted to twice earth’s radius above the surface of the earth, the value of g decreases by:

a) Two times b) Three times

c) Six times d) Nine times


Freely falling bodies are in a state of:

a) Rest b) Static equilibrium

c) Dynamic equilibrium d) Weightlessness


What is produced by spinning the spaceship around its own axis with a certain frequency which can provide centripetal force equal to the force of gravity at that point?

a) Weightlessness b) Artificial gravity

c) Vacuum d) None of the above


A bird resting on the floor of an air tight box which is being carried by a boy, starts flying. The boy will feel that the box is now:

a) Heavier in the beginning and lighter afterwards b) Lighter

c) Shows no change in weight d) Heavier afterwards


The minimum velocity required to go out from earth’s gravitational pull is called:

a) Terminal velocity b) Angular velocity

c) Drift velocity d) Escape velocity


The force of attraction acts along the:

a) Axis of rotation b) Line joining the interacting bodies

c) Line perpendicular to the interacting bodies d) None of these


A satellite is launched from earth into orbit. What happens to the mass & weight of the satellite?

Mass Weight Mass Weight

a) Decreases Decreases b) Decreases Stays constant

c) Stays constant Decreases d) Stays constant Stays constant


According to the law of Universal Gravitation:

Every body in the universe attracts every other body

The force of attraction is directly proportional to the product of their masses

The force of attraction is inversely proportional to the square of their distance

d) All of the above


The acceleration due to gravity on moon is 1/6th of that on earth, what will be the mass of the body on moon, if its mass on earth is m:

a) m/6 b) 6m

c) m d) m/3



Two masses 10 cm apart, attract each other with a force f Newtons. When 5 cm apart of these masses will attract each other with a force (in Newtons) of:

a) f/2 b) f/4

c) 4f d) 2f


If the earth were three times farther from the sun than it is now, the gravitational force exerted on earth by the sun will be:

a) Three times b) Nine times

c) One-ninth times d) One-third times


If the mass of the earth becomes four times large, the value of ‘g’ will:

a) Remain unchanged b) Becomes four times larger

c) Be doubled d) Become sixteen times larger


The gravitational acceleration is maximum on poles as compared to that on equator because:

Distance between poles and center of earth is less as compared to that between equator & center

Distance between poles and center of earth more as compared to that between equator and center

Mass of earth on poles is greater as compared to that on equator

d) Mass of earth on poles is less as compared to that on equator


An astronaut of weight mg is moving upwards in a rocket with acceleration 4g. His apparent weight in side that rocket will be:

a) zero b) mg

c) 3 mg d) 5 mg


When a lift is moving upward with a uniform velocity, the apparent weight of a body inside the lift will be:

a) Equal to its actual weight b) Less than the actual weight

c) More than the actual weight d) Zero


Free falling bodies:

a) Have maximum weight b) Have minimum weight

c) Have no weight d) Any weight


A boy standing in a lift falling freely under gravity releases a ball from his hand. As seen by him the ball:

a) Falls down b) Remains stationary

c) Goes up d) None of the above


A satellite moves in the circle orbit at the constant speed under the action of the gravitational force of a planet. The work done on the satellite in one revolution will have magnitude:

a) Zero b) Half of the gravitational pull of the planet

c) Equal to the gravitational pull of the planet d) Proportional to the diameter of the orbit


A body in satellite orbiting round the earth is weightless because:

It is essentially a freely falling body

It is far away from the earth to experience the pull of the earth

The moon attracts the body with a force equal to its weight

d) None of the above


Artificial gravity can be created in the space craft by:

a) Revolving it around the earth b) Spinning it around its own axis

c) Increasing its velocity d) Decreasing its velocity


When a man circles round the earth in a satellite, then:

His mass becomes zero but weight remains constant

His mass remains constant but weight becomes zero

Both mass and weight remain constant

d) Both mass and weight become zero


A space ship is coming towards earth from moon at a high speed. The speed of the air ship has to be reduced. The rocket is fired to lower its speed in which direction. The rocket should be fired:

a) In the direction towards the earth b) In the direction towards the moon

c) On the right side of space ship d) On the left side of space ship


The radius of earth 6 x 106 m. What is the acceleration of a meteor, when it is 8 x 106 m from the center of the earth?

a) 8 m/s2 b) 4 m/s2

c) 9.8 m/s2 d) None of above


A man whose weight is 900 N on the earth’s surface goes to a height, which is equal to twice the earth’s radius, above the surface of the earth, then the new weight of the man will be:

a) 900 N b) 225 N

c) 300 N d) 100 N


An object is taken from the earth to a planet where the value ‘g’ is 20 m/s2, if it is compared with value of ‘g’ earth, which of the following statement is true?

a) Weight at the planet will be greater b) Weight at the planet will be same

c) Mass at the planet will be greater d) Mass at the planet will be smaller


An air craft pulls out of a drive in a circular arc of radius 1000 m at speed 200 m/s, the apparent weight of the 80 kg pilot at the lowest point will be:

a) 3990 N b) 4264 N

c) 2920 N d) 3984 N