Physics

Gravitation and Orbital Mechanics

522 Questions

Gravitation and orbital mechanics focus on planetary motion, elliptical orbits, and satellite deployment. Questions examine astrodynamics fundamentals, including geostationary orbits and perturbation theory. These topics are highly relevant for civil services and specialized technical examinations.

Planetary orbitsSatellite dynamicsGeostationary orbitsPerturbation theoryOrbital eccentricity

Gravitation and Orbital Mechanics Questions

Multiple choice

Earth's revolution (orbit) takes approximately ...

  1. one day

  2. one month

  3. one year

  4. juan direction

Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Earth's revolution is the path it takes around the sun, which takes approximately 365.25 days, or one year. Option D is a humorous distractor.

Multiple choice physics universe and space science launching of an artificial satellites around the earth launching of satellite india’s space programmes

Communication satellites move in orbits of radius 44,400 km around the earth find the acceleration of such a satelite, assuming that the only force acting on, it is that  due to the earth.Mass of the earth $ = 6 \times {10^{24}}Kg.$

  1. $0.2\;m{s^{ - 2}}$
  2. $2.1\;m{s^{ - 2}}$
  3. $4.2\;m{s^{ - 2}}$
  4. $0.3\;m{s^{ - 2}}$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The acceleration (a) of a satellite in orbit is given by the gravitational field strength: a = GM / r^2. Using G = 6.67e-11, M = 6e24, and r = 4.44e7 meters, a = (6.67e-11 * 6e24) / (4.44e7)^2 = 4e14 / 1.97e15 = 0.203 m/s^2.

Multiple choice physics universe and space science launching of an artificial satellites around the earth launching of satellite india’s space programmes

In case of an orbiting satellite, if the radius of orbit is decreased.

  1. Its KE decreases

  2. Its PE decreases

  3. Its ME decreases

  4. Its speed decreases
Reveal answer Fill a bubble to check yourself
B,C Correct answer
Explanation

P.E of orbiting satellite at distance $r$ from centre of earth

$=\cfrac{-GMm}{r}\\K.E=\cfrac{GMm}{2R}$ and $M.E=\cfrac{-GMm}{2R}$

If $R$ decreased K.E increases.

P.E and M.E become more negative, thus decrease.

Multiple choice physics universe and space science launching of an artificial satellites around the earth launching of satellite india’s space programmes

Two identical satellites are moving in the same circular orbit around the earth but in opposite senses of rotation, Assuming an inelastic collision to take place, so that the wreckage remains as one piece of tangled material  wreckage

  1. will be moving in a circular orbit of half the radius

  2. will be moving in a circular orbit on one fourth the radius

  3. will spin with no translatory motion

  4. falls directly down
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The wreckage will spin with no translatory motion$.$

Hence,
option $(C)$ is correct answer.  

Multiple choice physics universe and space science launching of an artificial satellites around the earth launching of satellite india’s space programmes

Geo stationary satelites revolves at:

  1. Any height

  2. Fixed height

  3. Height above pole

  4. height which depends upon its mass
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Geo stationary satellite revolves at fixed height. A Geo stationary satellite is an earth orbiting satellite which is placed at an altitude of approximately 35,800 kms directly over the equator, that revolves in the same direction the earth rotates.

Multiple choice physics search of life outside earth space research and satellites artificial satellites space missions and artificial satellites

A satellite of mass $m$ revolving around the earth in a circular orbit of radius $2R$ has to be shifted to another circular orbit of radius $4R$. The energy required for this process will be ($M\rightarrow$ mass of earth, $R\rightarrow$ radius of the earth)

  1. $\dfrac {GMm}{8R}$
  2. $\dfrac {2GMm}{3R}$
  3. $\dfrac {GMm}{4R}$
  4. $\dfrac {GMm}{6R}$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The total energy of a satellite in an orbit of radius r is E = -GMm / (2r). The energy required to move from 2R to 4R is E2 - E1 = (-GMm / 8R) - (-GMm / 4R) = (-GMm + 2GMm) / 8R = GMm / 8R.

Multiple choice evs search of life outside earth space research and satellites artificial satellites space missions and artificial satellites

Remote imaging satellites are placed in geostationary orbit. This statement is

  1. True

  2. False
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Answer is A.
Geostationary satellites are positioned at an height above the Earth about $36,000\ km$. At this height, they rotate around the Earth at the same speed as the Earth rotates around its axis, so in effect remaining stationary above a point on the Earth (normally directly overhead the equator).
As they remain stationary, they are ideal for use as communications satellites and also for remote imaging as they can repeatedly scan the same points on the Earth beneath them.
Their great height is that they can view the whole Earth disk below them, rather than a small subsection, and they can scan the same area very frequently.
Hence, the statement is true.

Multiple choice physics gravitation elementary ideas of astronomy shadow formation and optical medium light and shadow

Suppose an earth satellite, revolving in a circular orbit experiences a resistance due to cosmic dust. Then.

  1. Its kinetic energy will increase

  2. Its potential energy will decrease

  3. It will spiral towards the earth and in the process its angular momentum will remain conserved

  4. Both a and b is correct
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation
The Kinetic energy of the satellite increases in spiral path as it approach the earth so $V$ must increase the total mechanical energy of the satellite decreases due to resistance from conic dust as satellite approaches earth so potential energy decreases.
Thus Kinetic energy increase potential energy decreases.
Multiple choice physics space missions launching of an artificial satellites around the earth launching of satellite india’s space programmes

ENERGY OF AN ORBITING SATELLITE
In motion of an object under the gravitational influence of another object. Which of the following quantities is not conserved?

  1. Angular momentum

  2. mass of an object

  3. Total mechanical energy

  4. Linear momentum
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

While considering the motion of an object under the gravitational influence of another object, angular momentum and total mechanical energy are conserved.Linear momentum is not conserved

Multiple choice physics space missions launching of an artificial satellites around the earth launching of satellite india’s space programmes

The minimum distance of a satellite from the centre of the earth is 3R, where R is the radius of 2GM What is the earth. The mass of earth is M. The maximum speed of the satellite is $\sqrt { \frac { 2 G M } { 3 R } }$ radius of curvature at the point of minimum distance?

  1. 6 R

  2. 4 R

  3. 3 R
  4. $\frac { 9 R } { 2 }$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

$\begin{array}{l} F=\dfrac { { G\left( M \right) m } }{ { { { \left( { 3R } \right)  }^{ 2 } } } }  \ \Rightarrow a=\dfrac { { GM } }{ { 9{ R^{ 2 } } } }  \ \therefore \dfrac { { { V^{ 2 } } } }{ { R' } } =a \ \Rightarrow \dfrac { { 2GM } }{ { 3R.R' } } =\dfrac { { GM } }{ { 9{ R^{ 2 } } } }  \ \Rightarrow R'=6R \ Hence, \ option\, \, A\, \, is\, \, correct\, \, answer. \end{array}$

Multiple choice lorentz transformation and muon experiment option a: relativity physics

Suppose a new planet is discovered, which revolves around the sun (i.e. it is a part of our solar system). If its lies between saturn and Jupitar, its time period of revolution would be 

  1. Less than that of Jupiter

  2. More than that of Jupiter

  3. Equal to that of Jupiter or saturn

  4. More than that of saturn.
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

We don't know the exact order of all the planets, but Jupiter formed first, with Saturn close behind. Both were finished in less than 3 million years. The inner planets (Mercury, Venus, Earth, Mars) got off to a late start.

Multiple choice physics artificial satellite communication and mass media understanding communication and impact of mass media satellites in communication

As the height of a satellite orbit gets lower, the speed of the satellite _________.

  1. decreases

  2. increases

  3. remains the same

  4. none of the above
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

$V=\sqrt { \cfrac { GMe }{ r }  } \ \therefore V\propto \cfrac { 1 }{ \sqrt { r }  } $

With decrease in $'r'$, velocity of satellite $increases$.

Multiple choice physics artificial satellite communication and mass media understanding communication and impact of mass media satellites in communication

Let $R _s$ and $R _m$ be the distance of the geostationary satellite and moon from the center of earth. Then $\dfrac{R _m}{R _s}$ is

  1. $(29)^{1/2}$
  2. $(29)^{2/3}$
  3. $29$
  4. $(29)^{3/2}$
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Using Kepler's Third Law, T^2 is proportional to R^3. For a geostationary satellite, T is 1 day. For the moon, T is approximately 29 days. Thus, (Rm/Rs)^3 = (Tm/Ts)^2 = (29/1)^2, which means Rm/Rs = (29^2)^(1/3) = 29^(2/3).