WBCHSE Class 11 Physics Newtonian Gravitation And Planetary Motion Very Short Answer Questions

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Newtonian Gravitation And Planetary Motion Very Short Answer Type Questions

WBBSE Class 11 Very Short Answer Questions on Gravitation

Question 1. What is the name of the mutual force acting between any two bodies in the universe?
Answer: Gravitation

Question 2. What is the value of G in the CGS system?
Answer:

The value of G in the CGS system

6.67 x 10-8 dyn · cm2 · g-2

Question 3. What is the unit of G in SI?
Answer:

The unit of G in SI

N · m2 · kg-2

Question 4. What is the unit of gravity in SI?
Answer:

The unit of gravity in SI

Newton or N

Question 5. State whether the value of g increases or decreases due to an increase in depth below the earth’s surface.
Answer: Decreases

Question 6. Does the friction arise due to gravitation?
Answer: No

Question 7. What will be the force of attraction of 1 kg lead on the earth and the force of attraction of the earth on 1 kg lead?
Answer: Equal

Question 8. What is the value of G in SI?
Answer:

The value of G in SI

6.67 x 10-11 N · m2 · kg-2

Question 9. What is the unit of G in the CGS system?
Answer:

The unit of G in the CGS system

dyn · cm2  · g-2

Question 10. What is the dimension of G?
Answer:

The dimension of G

M-1L3T-2

Question 11. ‘The gravitational force is a conservative force’ true or false?
Answer: False

Question 12. Is the gravitational force between two bodies in air equal to that inside water?
Answer: Yes

Newton’s Law of Gravitation VSA Questions

Question 13. Does gravitational force depend on temperature?
Answer: No

Question 14. State whether your weight will increase or decrease if the daily rotation of the earth ceases.
Answer: Increase

Question 15. What will be the gravitational potential on the surface of a planet of mass M and radius R?
Answer: –\(\frac{GM}{R}\)

Question 16. If the potential and kinetic energies of an artificial satellite revolving around the earth are U and K respectively, what will be the relation between U and K?
Answer: U = -2K

Question 17. If a body of mass m is at a distance r in the gravitational field of a body of mass M, what will be the gravitational potential energy of the body?
Answer: –\(\frac{G M m}{r}\)

Question 18. What is the weight of a body at the centre of the earth?
Answer: Zero

Question 19. What is the value of the acceleration due to gravity at the centre of the earth?
Answer: Zero

Question 20. Where does a body weigh more at the pole or at the equator?
Answer: At the pole

Question 21. What is the value of the acceleration due to gravity of all bodies (heavy or light) at a particular place?
Answer: Same

Question 22. Write down the relation between g and G.
Answer: g = \(\frac{G M}{r^2}\)

Question 23. What is the relation between the mean density of the earth and G?
Answer: \(\rho=\frac{3 g}{4 \pi G R}t\)

Question 24. Write down the variation of the acceleration due to gravity at a point above the surface of the earth to the square of the distance of that point from the centre of the earth.
Answer: Inversely proportional

Question 25. ‘The value of g at the poles is greater than its value at the equator.’—true or false?
Answer: True

Question 26. What is the value of the acceleration due to gravity on the surface of the earth?
Answer: Maximum

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Kepler’s Laws of Planetary Motion Short Answers

Question 27. The decrease in the acceleration due to gravity at a height above the earth’s surface is _______ the decrease in the acceleration due to gravity at the same depth below the surface of the earth.
Answer: Double

Question 28. The acceleration due to gravity at a height above the earth’s surface is ______ than that at the same depth below the surface of the earth.
Answer: Less

Question 29. Give the value of the angular velocity of the earth for which the acceleration due to gravity at the equator would be zero.
Answer: 1.24 x 10-3 rad · s-1

Question 30. If the diurnal motion of the earth ceases, write the variation of g at all places except at the poles.
Answer: Increase

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Question 31. If the angular velocity of the earth is increased, write the variation of g at all places except at the poles.
Answer: Decrease

Question 32. If the radius of the earth is halved keeping its mass unchanged, then the acceleration due to gravity would be _____ times its previous value.
Answer: 4

Question 33. During free fall, the weight of a body becomes _______
Answer: Zero

Question 34. What will be the value of acceleration due to gravity on the earth’s surface if its radius is decreased by 1%, keeping the mass unchanged?
Answer: Increase by 2%

Question 35. Where is the escape velocity of a body greater from the earth or from the moon?
Answer: From the earth

Question 36. How does the escape velocity of a body from the earth depend on the mass of the body thrown?
Answer: Does not depend on the mass of the body

Question 37. From the surface of a planet, the escape velocity of all bodies— heavy or light—is ________
Answer: Equal

Question 38. From the surface of the moon, give the value of the escape velocity.
Answer: 2.4 km · s-1

Question 39. What is the relation between orbital and escape velocity?
Answer: \(v_e=\sqrt{2 v_0}\)

Question 40. When a body coming from infinity falls on the earth’s surface, give its velocity.
Answer: \(\sqrt{2} g R\)

Question 41. The orbital speed of a planet around the sun depends on the mass of the planet—is this statement true or false?
Answer: False

Gravitational Potential Energy VSA Questions

Question 42. A comet orbits the sun in a highly elliptical orbit. Does the comet have a constant?

  1. Linear speed,
  2. Angular speed,
  3. Angular momentum,
  4. Kinetic energy,
  5. Potential energy,
  6. Total energy throughout its orbit?

Neglect any mass loss of the comet when it comes very close to the sun.

Answer:

  1. Not a constant,
  2. Not a constant,
  3. Constant,
  4. Not a constant,
  5. Not a constant,
  6. Constant.

Question 43. The time period of revolution of an artificial satellite in an orbit just outside the equatorial plane depends only on the mean density of the earth. Is this statement true or false?
Answer: True

Question 44. An artificial satellite appears to be stationary with respect to an observer on the earth. At what height (approx.) above the earth’s surface is it placed?
Answer: 36000 km

Question 45. What is the name of the orbit where an artificial satellite appears to be at rest from the Earth?
Answer: Parking orbit

Question 46. What time will a polar satellite take to revolve around the earth once?
Answer: 2h

Question 47. In which plane of the earth, does the orbit of a geostationary satellite always lie?
Answer: Equatorial plane

Question 48. Write down one most important applications of geostationary satellites.
Answer: As a communication satellite

Question 49. Assuming that the earth revolves around the sun in a circular orbit, the line joining the earth and the centre of its orbit covers ______ area.
Answer: Constant

Question 50. If the distance between the sun and the earth were half the present value, the span of a year would be __________ days.
Answer: 129

Question 51. If two satellites revolve in two different circular orbits, the orbital speed of the external satellite will be _______ than that of the inner satellite.
Answer: Less

Acceleration Due to Gravity Short Answer Questions

Question 52. ‘The orbital speed of a satellite of the earth does not depend on the mass of the satellite’— true or false
Answer: True

Question 53. Two satellites A and B are revolving around the Earth at the same height. The mass of the satellite A is twice that of B. What will be the speed of A that of B?
Answer: Equal

Question 54. If the orbital speed of an artificial satellite revolving very close to the earth is v and the escape velocity from the surface of the earth is ve, then ve = _________ x v.
Answer: √2

Question 55. A geostationary satellite orbits the earth once in 24 h in the __________ of the diurnal motion of the earth.
Answer: Direction

Question 56. If the radius of the earth is R, what will be the distance of a geostationary satellite from the centre of the earth?
Answer: Approximately 7R

Question 57. A person inside an artificial satellite revolving around the earth feels weightless’—true or false?
Answer: True

Question 58. The orbit of a polar satellite lies in the __________ plane.
Answer: Polar meridian

Question 59. The total energy of an artificial satellite of mass m revolving around the earth of mass M is _________. The radius of the orbit of the satellite = r.
Answer: –\(\frac{G M M}{2 r}\)

Question 60. What will be the length of a year if the distance between the earth and the sun is increased to twice the present value?
Answer: 1032 days

Question 61. What is the dimension of gravitational intensity?
Answer:

Short Answers on Orbital Motion for Class 11

The dimension of gravitational intensity

LT-2

Question 62. What is the unit of the intensity of the gravitational field?
Answer:

The unit of the intensity of the gravitational field

N · kg-1

Question 63. Where is the weight of a body greater—at the equator or at the poles?
Answer: At the poles

Question 64. State whether your weight will increase or decrease if the angular velocity of the earth increases.
Answer: Decrease

Escape Velocity Very Short Answer Questions

Question 65. State whether the value of g increases or decreases if one moves from the equator to the pole.
Answer: Increases

Question 66. Where on the surface of the earth is the value of g least due to the diurnal motion of the earth?
Answer: At the equator

Question 67. If the force of gravity ceases to act suddenly, then all bodies would become weightless’—true or false?
Answer: True

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