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Q1. Kepler's law of areas can be understood as a consequence of:

• conservation of angular momentum
• conservation of linear momentum
• conservation of energy
• conservation of mass

Solution

Kepler's law of areas can be understood as a consequence of conservation of angular momentum. L is constant as no torque acts on the planet so the rate at which it traverses an area is constant.

Q2. India's first artificial satellite was:

• Sputnik
• Aryabhatta
• Rohini
• Insat

Solution

India's first artificial satellite was Aryabhatta.

Q3. The energy required to be spent by a satellite of mass m and speed v and orbital radius r in completing a circular orbit once round the Earth of mass M is

• GMm/r
• GMm/2r
• zero
• 2GMm/r

Solution

Centripetal force does no work; hence energy required is zero.

Q4. Gravitation follows:

• Principle of Superposition
• Newton's Third Law of Motion
• Both A and B
• Neither A nor B

Solution

Gravitation follows both Principle of Superposition as well as Newton's Third Law of Motion.

Q5. Gravitational force is a

• Strong force
• Weak force
• Another kind of electric force
• Force existing only between the earth and human beings living on it

Solution

Gravitation is a weak force but a very important force responsible for various natural phenomena on earth as well as across the universe.

Q6. Two satellites S and S1 revolve around the Earth at distances 3R and 6R from the centre of Earth. Their periods of revolutions will be in the ratio:

• 1:2
• (1:2)^1/2
• (1:2)^1.5
• (1:2)^0.67

Solution

Q7. Binding energy of a satellite is

• - [total energy of satellite]
• potential energy of satellite
• kinetic energy of satellite
• total energy of satellite

Solution

The binding energy is the negative of the total energy of the satellite.  

Q8. Different planets have different escape velocities because:

• they have different distances from sun
• they have different masses and sizes
• escape velocity depends on the body that has to escape the atmosphere of the planet
• different planets have different atmosphere

Solution

Different planets have different escape velocities because they have different masses and sizes.

Q9. Which statement is not true about the gravitational forces?

• Gravitational forces are independent of presence or absence of another body
• Gravitational forces are independent of the medium
• Gravitational forces do not form action and reaction pair
• Gravitational forces are conservative forces

Solution

All the statements are true except the statement (C) as gravitational force between two bodies form an action and reaction pair and obey Newton’s third law of motion.

Q10. Weightlessness is:

• a situation in which the effective weight of the body becomes zero.
• a situation in which the effective mass of the body becomes zero.
• a situation in which the effective weight of the body becomes 10N.
• a situation in which the effective weight of the body becomes 9.8N.

Solution

Weightlessness is a situation in which the effective weight of the body becomes 0.

Q11. If r represents the radius of the orbit of the satellite of mass m moving around planet of mass M, the velocity v of the satellite is given by

• v²=GM/r
• v = GM/r
• v² = FMm/r
• v = Gm/r

Solution

GMm/r² = mv²/r v² = GM/r

Q12. When a satellite moves in a circular orbit, the _______acceleration is provided by the gravitational attraction of the Earth.

• centrifugal
• tangential
• fictitious
• centripetal

Solution

Centripetal; as the object moves along the circular orbit the gravtitational attraction continuously acts along the line joining the masses and is directed towards the centre of the Earth.

Q13. If a planet revolves around the Sun which of the following doesn't remain constant?

• Total energy
• Linear speed
• Angular momentum
• Angular momentum and Total energy

Solution

If a planet revolves around the Sun then linear speed doesn't remain constant.

Q14. A boy can jump 2 m on the surface of earth. How much can he jump on the surface of moon assuming that g on moon is 1/5 that of earth.

• 2 m
• 5 m
• 10 m
• 2/5 m

Solution

Q15. The value of escape velocity on earth when the body is thrown making an angle of 45^o with the horizontal is

• 11.2 km/s
• 11.2 × (2)^1/2 km/s
• 11.2 × (2)^1/4 km/s
• 22.4 km/s

Solution

The escape speed is independent of the angle of projection, and for Earth's surface, its value is 11.2 km/s. So, it remains constant.

Q16. What could be the maximum value for gravitational potential energy?

• infinity
• zero
• 1000
• 1

Solution

Q17. Escape velocity is:

• The minimum velocity with which the body has to be projected vertically upwards from the surface of the earth so that it crosses the gravitational field of earth and never returns back on its own.
• The maximum velocity with which the body has to be projected vertically upwards from the surface of the earth so that it crosses the gravitational field of earth and returns back.
• The maximum velocity with which the body has to be projected vertically upwards from the surface of the earth so that it crosses the gravitational field of earth and never returns back on its own.
• The minimum velocity with which the body has to be projected vertically upwards from the surface of the earth so that it crosses the gravitational field of earth and returns back.

Solution

Escape velocity is the minimum velocity with which the body has to be projected vertically upwards from the surface of the earth so that it crosses the gravitational field of earth and never returns back on its own.

Q18. In orbit, objects inside a spacecraft feel weightless

• as objects inside are in free fall because they have the same acceleration as outside the spacecraft
• as acceleration due to gravity is zero in space
• as acceleration due to gravity is less in spacecraft
• as mass of objects becomes zero

Solution

As objects inside are in free fall because they have the same acceleration as outside the spacecraft.

Q19. The squares of the periods of revolution of the planets are proportional to the ___________of their semimajor axis of its orbit.

• cubes
• squares
• square root
• cube root

Solution

The squares of the periods of revolution of the planets are proportional to the cubes of their semimajor axis of its orbit. This is a statement of Kepler's third law.

Q20. What is gravitational potential?

• It is defined as the work done in taking a unit mass from infinity to that point.
• It is defined as the work done in taking 100kg mass from infinity to that point.
• It is defined as the work done in taking a unit mass from one point to that point.
• It is defined as the energy spent in taking a unit mass from infinity to that point.

Solution

Gravitational Potential is defined as the work done in taking a unit mass from infinity to that point.

Q21. An Earth satellite is moved from one stable circular orbit to a farther stable circular orbit. which one of following quantity increases

• linear orbital speed
• gravitationl force
• centripetal acceleration
• gravitational potential energy

Solution

Gravitational potential energy as the distance increases.

Q22. Two bodies with same mass "m" separated by a distance "r" exert a gravitational force of F on each other. Suppose the distance between them is doubled and the force becomes F'. The ratio of two forces is

• 1 : 4
• 4 : 1
• 2 : 1
• 1: 2

Solution

Q23. A body of mass m rises to a height h = R/5 from the earth's surface where R is Earth's radius. If g is acceleration due to gravity , the increase in PE is

• mgh
• 4mgh/5
• 5mgh/6
• 6mgh/7

Solution

Q24. Which is untrue about orbital velocity?

• increases with the decrease in height of satellite
• it is independent of mass of satellite
• depends on mass and radius of planet around which it revolves
• decreases with an increase in radius of orbit

Solution

The orbital velocity is  Hence, all options are true except option (a).

Q25. Calculate the escape velocity on the surface of the planet of 5.3 x 10²⁰ grams, with radius 1.3 x 10⁵ m.

• 2.33 x 10³ m/s
• 2.33 m/s
• 23.3 m/s
• 2.33 x 10⁴ m/s

Solution

Q26. According to Newton's Law of Gravitation:

• Every body in the universe attracts every other body with a force which is directly proportional to the product of their masses and inversely proportional to the square of the distance them
• Every body in the universe attracts every other body with a force which is inversely proportional to the product of their masses and inversely proportional to the square of the distance them
• Every body in the universe attracts every other body with a force which is directly proportional to the product of their masses and directly proportional to the square of the distance them
• Every body in the universe attracts every other body with a force which is inversely proportional to the product of their masses and inversely proportional to the square of the distance them

Solution

Every body in the universe attracts every other body with a force which is directly proportional to the product of their masses and inversely proportional to the square of the distance them.

Q27. Weight is

• The force with which an object is pulled towards the centre of the Earth.
• The force with which an object is pushed towards the centre of the Earth.
• The energy with which an object is pulled towards the centre of the Earth.
• The force with which an object is pulled towards the centre of the Sun.

Solution

Weight is the force with which an object is pulled towards the centre of the Earth.

Q28. Gravitational Potential is:

• negative, vector quantity , unit JKg^-1
• negative, scalar quantity , unit JKg^-1
• positive, scalar quantity , unit JKg^-1
• positive, vector quantity , unit JKg^-1

Solution

Gravitational Potential is negative, scalar quantity, unit JKg^-1.

Q29. A single polar satellite can monitor ­­­­____ of earth's surface

• 0%
• 50%
• 100%
• 15%

Solution

A single polar satellite can monitor ­­­­100% of earth's surface.

Q30. The mass of the moon is 1/81 of earth's mass and its radius 1/4 that of earth. If the escape velocity from the earth's surface is 11.2 km/s ,its value for the moon...

• 0.14 km/s
• 0.5 km/s
• 2.5 km/s
• 5.0 km/s

Solution

Q31. An unmanned space probe is to be thrown with such a velocity that it does not return back to Earth. It should be thrown with:

• velocity = (2GM)^1/2/R
• velocity > (2GM)^1/2/ R necessarily
• velocity ≥ (2GM/R)^1/2
• a great velocity but nothing more can be said

Solution

An unmanned space probe should be thrown with velocity ≥ (2GM/R)^1/2 so that it does not return back to earth.

Q32. A satellite which appears to be at a fixed position at a definite height to an observer is called:

• Geostationary satellite
• Polar satellite
• Geoorbit satellite
• Stationary satellite

Solution

A satellite which appears to be at a fixed position at a definite height to an observer is called a geostationary satellite or a geosynchronous satellite.

Q33. If a planet exists whose mass and radius were half that of earth,the acceleration due to gravity at its surface would be:

• 8 ft/s²
• 16 ft/s²
• 32 ft/s²
• 64 ft/s²

Solution

Q34. The force of attraction due to a hollow spherical shell of uniform density, on a point mass situated inside it

• depends on the mass of the shell
• depends on mass of point mass
• depends on mass of shell and point mass
• zero

Solution

The forces in all directions cancel each other out and net force is zero.

Q35. Escape velocity does not depend on:

• Mass of body only
• Direction of projection of body only
• Both mass and Direction of projection of body
• Mass of the planet or earth

Solution

Escape velocity does not depend on mass of the body as well as the direction of projection of the body. It only depends on the mass and the radius of the planet or Earth from where the body is to be projected.

Q36. A satellite moves in a circular orbit around Earth. The radius of this orbit is one half that of Moon's orbit. The satellite completes one revolution in:

• (2)^1/2 lunar month
• (2)^3/2 lunar month
• (2)^2/3 lunar month
• (2)³ lunar month

Solution

Q37. The tides are formed due to:

• Force of attraction between earth and ocean water
• Movement of Wind
• Force of attraction between earth and ocean water and movement of wind
• Force of attraction between moon and ocean water

Solution

The tides are formed due to force of attraction between moon and ocean water.

Q38. The gravitational potential due to the gravitational force on the Earth is defined as the

• potential energy of the mass placed at that point
• potential energy of a unit mass at that point
• numerically equal to the potential energy
• potential energy multiplied by the mass of the object

Solution

It is the potential energy of a unit mass at that point.

Q39. Kepler's second law states that the straight line joining the planet to the sun sweeps out equal areas in equal time. The statement is equivalent to saying that:

• total acceleration is zero
• transverse acceleration is zero
• longitudnal acceleration is zero
• radial acceleration is zero

Solution

The statement is equivalent to saying that transverse acceleration is zero.

Q40. The dimensions of gravitational constant G is

• [L][M][T]
• [L] ³[M]^-1[T]^-2
• [L]³[T]^-2
• [L]³[M][T]²