Free Satellite Motion and Orbital Velocity MCQs with Answers
26 Satellite Motion and Orbital Velocity MCQs from Physics, each with the correct answer and a written explanation of why it is correct. Free and unlimited, with no account needed.
Satellite motion uses gravitational force as the centripetal force required for circular orbit, giving relationships among orbital radius, period and orbital velocity. Questions cover geostationary conditions and weightlessness, while distinguishing orbital velocity, escape velocity and the satellite's tangential speed.
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21. The time period of communication satellites is:
- A. 1 hour
- B. 2 hour
- C. 12 hours
- D. 24 hours
Explanation: 24 hours: This option is correct. Geostationary communication satellites orbit the Earth at a height of about 35,786 kilometers, taking 24 hours to complete one orbit. This allows them to remain fixed in the sky relative to an observer on Earth, providing continuous communication coverage.
Correct answer: 24 hours22. The escape velocity from the earth gravitational field depends upon:earth's
- A. rotation of earth
- B. mass of body
- C. radius of earth
- D. mass of earth
Explanation: Escape velocity, Ve =√( 2GM/R) Acceleration due to gravity, g= GM/R², which is always constant. Plugging this value of g in the first equation: Ve= √2gR , where R is the radius of the earth . From the above equation, we see escape velocity is dependent upon is gravitational acceleration and radius of the earth so option C is correct.
Correct answer: radius of earth23. The Geostationary satellites are
- A. stationary
- B. Rotating with the speed of earth
- C. rotating very fastly
- D. rotating very slowly
Explanation: Geostationary satellites remain at the same position with respect to the Earth, so that they scan the same place in a better way. Therefore, the relative velocity of geostationary satellite with respect to the spinning motion of the Earth is 0 m/s.
Correct answer: Rotating with the speed of earth24. Satellites revolve around the earth in a circular orbit. What is the relationship between the radius of their orbits and their speeds?
- A. V ∞ r2
- B. V ∞ r
- C. V1 ∞ 1/r
- D. V ∞ 1/r2
Explanation: d) V ∞ 1/r^2 (V is proportional to 1/r^2):This option correctly represents the relationship between the speed (V) of a satellite and the radius (r) of its orbit. The speed of a satellite is inversely proportional to the square of the radius of its orbit. This means that as the radius of the orbit increases, the speed of the satellite decreases, and vice versa.
Correct answer: V ∞ 1/r225. A satellite is orbiting close to the surface of the earth, its speed is
- A. √2gR
- B. √Rg
- C. Rg/2
- D. Rg
Explanation: The force on a mass m, having an angular velocity ω orbiting in a circular path of radius R is F=mRω2. But v=ω R, where v is the linear velocity so F=mv2/R. Equating this with the weight of the body we get, mg=mv2 /R. Or, v2 = Rg. Or, v=√(Rg)
Correct answer: √Rg26. Two satellites of masses "3M" and "M" orbit the earth in a circular orbit of radius Y and "3r" respectively, the ratio of their speed is:
- A. 1:1
- B. Square root of 3 :1
- C. 3:1
- D. 9:1
Explanation: To move in a circular orbit, gravitational force provides centripetal force. Gravitational force between the two is the same as it is a mutual force. For the same reason, distance between the satellites is the same so speed does not depend on radius.
Correct answer: Square root of 3 :1