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 general knowledge science & technology

If the force of gravity suddenly stopped acting on the planets, they would….

  1. Fly straight away from the Sun

  2. Continue to orbit the Sun

  3. Spiral slowly towards the Sun

  4. Move in a straight line tangent to their orbit
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Planets orbit the Sun due to gravity providing the centripetal force. If gravity disappeared, Newton's First Law states they would continue moving in a straight line (tangent to their orbit at that instant) with whatever velocity they had.

Multiple choice general knowledge

What is the difference between Earth's rotation and revolution

  1. Revolution refers to Earth's spinning on its axis, and rotation refers to Earth's changing seasons.

  2. Rotation refers to Earth's spinning on its axis, and revolution refers to Earth's spinning around the Sun.

  3. Rotation refers to Earth's spinning on its equator, and revolution refers to Earth's spinning around the solar system.

  4. Revolution refers to Earth's spinning on its axis, and rotation refers to Earth's spinning around the Sun.
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Rotation is Earth's spinning on its axis, which takes approximately 24 hours and creates day and night. Revolution is Earth's orbital motion around the Sun, which takes about 365.25 days and creates the year. Option A has the definitions swapped. Option C incorrectly mentions spinning on the equator instead of the axis, and its description of revolution is nonsensical. Option D also swaps the correct definitions.

Multiple choice general knowledge

Why doesn't Earth's orbit cause seasonal temperature changes on Earth?

  1. The change in distance is actually minimal. Earth's tilted axis is the real cause of seasons on Earth.

  2. Even though Earth's orbit is an ellipse, the change in distance from the Sun is only an optical illusion.

  3. The change in distance is the real cause of seasons on Earth.

  4. The change in distance occurs at the same time as the seasons, so we don't notice the change.
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Earth's orbit is nearly circular with only about 3% variation in distance throughout the year - from 147 million km at perihelion to 152 million km at aphelion. This small change cannot explain seasonal temperature differences. Instead, Earth's 23.5-degree axial tilt means different parts of Earth receive varying solar intensity at different times of year. Option B is wrong - the orbital shape change is real, not an illusion. Option C is factually incorrect. Option D is illogical - timing correlation doesn't explain causation.

Multiple choice general knowledge science & technology

HOW LONG IS A YEAR IN SATURN

  1. 256.9

  2. 168.3

  3. 16.8

  4. 29.5
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

A year on Saturn (the time it takes to complete one orbit around the Sun) is approximately 29.5 Earth years. This is because Saturn is much farther from the Sun than Earth and follows a larger orbital path according to Kepler's laws of planetary motion. The other options (256.9, 168.3, and 16.8) do not match the actual orbital period of Saturn.

Multiple choice general knowledge science & technology

To reach another planet, a spacecraft must be aimed:

  1. At the planet

  2. Midway between the two

  3. Where the planet will be when the spacecraft reaches it

  4. Near the planet
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Spacecraft must be aimed where the target planet will be at arrival, not where it is at launch. Planets move at different speeds along their orbits, so intercept calculations require precise timing. This is why launch windows occur at specific intervals. Aiming directly at the planet's current position would cause the spacecraft to miss because the planet will have moved by arrival time.

Multiple choice general knowledge science & technology

Planets have elliptical orbits. This means that

  1. Their orbits are perfectly round.

  2. Their orbits are in the shape of a figure eight.

  3. At some point of its orbit, a planet is closer to the sun.

  4. Their orbits change direction from time to time.
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Elliptical orbits are oval-shaped, not circular. According to Kepler's First Law, planets orbit the sun in ellipses with the sun at one focus. This means the distance from the sun varies, with the closest point called perihelion and farthest called aphelion. The orbit doesn't change direction randomly or form a figure-eight.

Multiple choice general knowledge science & technology

To reach another planet, a spacecraft must be aimed:

  1. At the planet

  2. Where the planet will be when the spacecraft reaches it

  3. Midway between the two

  4. Some distance before the planet
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Because spacecraft travel time takes months or years and planets move continuously along their orbits, you must aim where the planet will be when the spacecraft arrives. This is called 'leading the target' - similar to shooting a moving object in hunting.

Multiple choice general knowledge science & technology

How many times has our solar system orbitted the centre of the galaxy?

  1. Not yet once

  2. 20

  3. 1000

  4. 1 million
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Our solar system has orbited the center of the Milky Way galaxy approximately 20 times since its formation 4.6 billion years ago. One galactic orbit (galactic year) takes about 230 million years. The options of 'not yet once', '1000', and '1 million' are all incorrect estimates.

Multiple choice general knowledge science & technology

The moons period of rotation is exactly the same as it's period of orbit.

  1. True

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

The Moon is tidally locked to Earth, meaning its rotational period (27.3 days) exactly matches its orbital period (27.3 days). This synchronous rotation is why we always see the same side of the Moon from Earth. The phenomenon results from gravitational forces slowing the Moon's rotation over billions of years.

Multiple choice general knowledge science & technology

On Mercury a day (the time it takes for it to spin round once) is ___ Earth-days.

  1. 56

  2. 57

  3. 58

  4. 59
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Mercury's rotational period (sidereal day) is approximately 58.6 Earth days. This means Mercury takes about 59 Earth days to complete one rotation on its axis. Due to its 3:2 spin-orbit resonance with the Sun, a Mercury solar day (sunrise to sunrise) lasts about 176 Earth days.

Multiple choice general knowledge science & technology
  1. To reach another planet, a spacecraft must be aimed:

  1. At the planet

  2. Midway between the two

  3. Where the planet will be when the spacecraft reaches it

  4. all the above
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

A spacecraft must be aimed at where the planet will be when the spacecraft arrives, not where it is now. Both the spacecraft and target planet are moving in their orbits, so you must calculate the planet's future position at arrival time. Aiming at the planet's current position would cause the spacecraft to arrive where the planet used to be. 'Midway' makes no sense for intercept trajectories.

Multiple choice technology

How many GPS satellites are currently functioning in space

  1. 30

  2. 24

  3. 6

  4. 18
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The GPS constellation requires at least 24 satellites for full global coverage (4 visible from any point), but currently 30 operational satellites are maintained in orbit. This includes spares and backups to ensure reliability as older satellites fail and new ones are launched.

Multiple choice

Fill blank (ix).

Directions: Read the following passage and fill the numbered blanks using correct option.

Asteroids are rocks and debris which are the leftovers of the construction of our solar system. Most are in a belt, which ___(i)___ between Mars and Jupiter. However, the gravitational influence of the giant planets, like Jupiter, or an impact by a comet can knock these large rocks out of their orbit, thus hurling them ___(ii)___ the Earth. Many bodies have struck Earth in the ___(iii)___, and a widely accepted theory blames the impact of an asteroid for the extinction of dinosaurs about 65 million years ago. The scale of such a disaster can be understood by the example of a relatively small-size asteroid strike in Siberia in early 20th century which ___(iv)___ more than half a million acres of forest.
However, what relieves the common, man of the ___(v)___ regarding asteroid impact is the fact that many scientific groups are dedicated towards tracking the asteroid paths and orbit all around the year. With advanced equipments and technology, they can predict any upcoming danger much in ___(vi)___.
According to them the chances of finding such an asteroid crossing Earth in this or the next five generation’s lifetime is only one in thousands. Even if such an asteroid is found out, there will be ___(vii)___ of time to track it, measure its orbit precisely, and plan a system for ___(viii)___ it from its orbit away from that of the Earth’s. There will be no great hurry, and no great panic. It would be a project for all the world’s nations to take part in. It could be a globally unifying event. Because it will be ___(ix)___ long before it actually hits the Earth. It probably would take only a small measure such as chemical rockets, or perhaps an atomic explosion to divert it from a threatening path. Thus, in short, it can be said that though the impact would pose enormous risk to all living forms on Earth, the odds of it occurring within our lifetimes is very ___(x)___ and it is unnecessary to run around believing that the sky is falling.

  1. experienced

  2. harmful

  3. perceived

  4. noticed

  5. devastating
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

With advancement in technology, we are able to see or notice changes in the space, changes in the movements of any object in space. As we can see, correct option will be noticed. Other options are out of context.