**Q1. 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.

**Answer :- (1)**

**Q2. 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

**Answer :- (4)**

**Q3. 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

**Answer :- (3)**

**Q4. 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

**Answer :- (3)**

**Q5. When a satellite moves in a circular orbit, the _______acceleration is provided by the gravitational attraction of the Earth.**

- centrifugal
- tangential
- fictitious
- centripetal

**Answer :- (4)**

**Q6.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

**Answer :- (2)**

**Q7. 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

**Answer :- (3)**

**Q8. 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.

**Answer :- (1)**

**Q9. 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

**Answer :- (3)**

**Q10. 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}

**Answer :- (2)**

**Q11. 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/s
^{2} - 16 ft/s
^{2} - 32 ft/s
^{2} - 64 ft/s
^{2}

**Answer :- (4)**

**Q12.A body is projected with velocity ‘v’ from a planet with escape velocity ‘v _{e}‘. What will happen if v < v_{e}?**

- Body will leave the planets atmosphere and never come back
- Will reach certain height and orbit around planet necessarily
- Fall back on the planet necessarily
- Will either reach certain height and orbit around planet or fall back on the planet

**Answer :- (4)**

**Q13. Calculate the escape velocity on the surface of the planet of 5.3 x 10 ^{20} grams, with radius 1.3 x 10^{5 }m.**

- 2.33 x 10
^{3}m/s - 2.33 m/s
- 23.3 m/s
- 2.33 x 10
^{4}m/s

**Answer :- (3)**

**Q14. 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

**Answer :- (2)**

**Q15. A single polar satellite can monitor ____ of earth’s surface**

- 0%
- 50%
- 100%
- 15%

**Answer :- (3)**

**Q16.India’s first artificial satellite was:**

- Sputnik
- Aryabhatta
- Rohini
- Insat

**Answer :- (2)**

**Q17. 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

**Answer :- (2)**

**Q18. 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

**Answer :- (3)**

**Q19. Gravitation follows:**

- Principle of Superposition
- Newton’s Third Law of Motion
- Both A and B
- Neither A nor B

**Answer :- (3)**

**Q20. What does the term escape speed of a planet mean?**

- The minimum speed of an object to reach a height equal to the radius of the planet.
- The maximum speed required for an object to reach infinity.
- The minimum speed required for an object such that it does not return back to Earth.
- Cannot be defined

**Answer :- (3)**

**Q21. A 12 kg body attracts a sphere of 4 kg with 14 N force. Calculate the distance between the two bodies.**

- 1.51 x 10
^{-5}m - 1.51 x 10
^{-4}m - 15.1 x 10
^{-4}m - 15.1 x 10
^{-5}m

**Answer :- (1)**

**Q22. 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

**Answer :- (1)**

**Q23. 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

**Answer :- (1)**

**Q24. 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

**Answer :- (4)**

**Q25. 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

**Answer :- (3)**

**Q26. 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**

- v
^{2}=GM/r - v = GM/r
- v
^{2}= FMm/r - v = Gm/r

**Answer :- (1)**

**Q27. 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

**Answer :- (2)**

**Q28. 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

**Answer :- (3)**

**Q29. 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.

**Answer :- (1)**

**Q30. 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

**Answer :- (1)**

**Q31. What could be the maximum value for gravitational potential energy?**

- infinity
- zero
- 1000
- 1

**Answer :- (2)**

**Q32. 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}

**Answer :- (2)**

**Q33. 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.

**Answer :- (1)**

**Q34. 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

**Answer :- (3)**

**Q35. 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

**Answer :- (1)**

**Q36. 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

**Answer :- (2)**

**Q37. 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

**Answer :- (1)**

**Q38.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

**Answer :- (2)**

**Q39. 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

**Answer :- (1)**

**Q40. 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}

**Answer :- (3)**