Keplerian Motion

Description: Keplerian Motion is the motion of an object in space under the influence of a central gravitational force. This quiz will test your understanding of Kepler's Laws of Planetary Motion and their application in astrodynamics.
Number of Questions: 15
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Tags: astrodynamics kepler's laws orbital mechanics
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Which of Kepler's Laws states that a planet's orbit around the Sun is an ellipse, with the Sun at one of the foci?

  1. First Law

  2. Second Law

  3. Third Law


Correct Option: A
Explanation:

Kepler's First Law, also known as the Law of Ellipses, describes the shape of a planet's orbit around the Sun. It states that the orbit is an ellipse, with the Sun at one of the foci.

According to Kepler's Second Law, what is the relationship between a planet's distance from the Sun and its orbital velocity?

  1. Inversely proportional

  2. Directly proportional

  3. Constant


Correct Option: A
Explanation:

Kepler's Second Law, also known as the Law of Equal Areas, states that a planet's orbital velocity is inversely proportional to its distance from the Sun. This means that as a planet moves closer to the Sun, its velocity increases, and as it moves farther away, its velocity decreases.

Kepler's Third Law relates the orbital period of a planet to what property of its orbit?

  1. Eccentricity

  2. Semi-major axis

  3. Inclination


Correct Option: B
Explanation:

Kepler's Third Law states that the square of a planet's orbital period is directly proportional to the cube of its semi-major axis. This means that the farther a planet is from the Sun, the longer it takes to complete one orbit.

What is the eccentricity of a circular orbit?

  1. 0

  2. 1

  3. 0.5


Correct Option: A
Explanation:

Eccentricity is a measure of how elliptical an orbit is. A circular orbit has an eccentricity of 0, while an elliptical orbit has an eccentricity greater than 0 and less than 1.

What is the period of a geostationary orbit around Earth?

  1. 24 hours

  2. 12 hours

  3. 36 hours


Correct Option: A
Explanation:

A geostationary orbit is an orbit around Earth with a period of 24 hours, which means that the satellite appears to remain stationary over a fixed point on Earth's surface.

What is the orbital velocity of a satellite in a circular orbit at a distance of 6378 km from the center of Earth?

  1. 7.9 km/s

  2. 11.2 km/s

  3. 9.8 km/s


Correct Option: A
Explanation:

The orbital velocity of a satellite in a circular orbit can be calculated using the formula v = sqrt(GM/r), where G is the gravitational constant, M is the mass of the central body, and r is the distance from the center of the body. For Earth, G = 6.674×10^-11 m^3 kg^-1 s^-2, M = 5.972×10^24 kg, and r = 6378 km + satellite's altitude.

Which of the following is not a Keplerian element?

  1. Semi-major axis

  2. Eccentricity

  3. Inclination

  4. Argument of periapsis


Correct Option: D
Explanation:

The argument of periapsis is not a Keplerian element. The Keplerian elements are the six parameters that uniquely define the orbit of a celestial body around another body.

What is the transfer orbit used to move a satellite from one circular orbit to another?

  1. Hohmann transfer orbit

  2. Bi-elliptic transfer orbit

  3. Gauss transfer orbit


Correct Option: A
Explanation:

The Hohmann transfer orbit is a transfer orbit used to move a satellite from one circular orbit to another. It is the most efficient transfer orbit in terms of fuel consumption.

What is the velocity change required to transfer a satellite from a circular orbit of radius r1 to another circular orbit of radius r2?

  1. sqrt(2GM/r1) - sqrt(2GM/r2)

  2. sqrt(2GM/r1) + sqrt(2GM/r2)

  3. sqrt(GM/r1) - sqrt(GM/r2)


Correct Option: A
Explanation:

The velocity change required to transfer a satellite from a circular orbit of radius r1 to another circular orbit of radius r2 is given by the formula Δv = sqrt(2GM/r1) - sqrt(2GM/r2).

What is the orbital period of a satellite in an elliptical orbit with semi-major axis a and eccentricity e?

  1. 2πa^3/GM

  2. 2πa^2/GM

  3. 2πa/GM


Correct Option: A
Explanation:

The orbital period of a satellite in an elliptical orbit with semi-major axis a and eccentricity e is given by the formula T = 2πa^3/GM, where G is the gravitational constant and M is the mass of the central body.

What is the true anomaly of a satellite at a given point in its orbit?

  1. The angle between the periapsis and the current position of the satellite

  2. The angle between the apoapsis and the current position of the satellite

  3. The angle between the ascending node and the current position of the satellite


Correct Option: A
Explanation:

The true anomaly of a satellite at a given point in its orbit is the angle between the periapsis and the current position of the satellite.

What is the argument of periapsis of a satellite?

  1. The angle between the ascending node and the periapsis

  2. The angle between the ascending node and the apoapsis

  3. The angle between the periapsis and the apoapsis


Correct Option: A
Explanation:

The argument of periapsis of a satellite is the angle between the ascending node and the periapsis.

What is the inclination of a satellite's orbit?

  1. The angle between the orbital plane and the equatorial plane

  2. The angle between the orbital plane and the ecliptic plane

  3. The angle between the orbital plane and the plane of the vernal equinox


Correct Option: A
Explanation:

The inclination of a satellite's orbit is the angle between the orbital plane and the equatorial plane.

What is the ascending node of a satellite's orbit?

  1. The point where the orbit crosses the equatorial plane from south to north

  2. The point where the orbit crosses the equatorial plane from north to south

  3. The point where the orbit crosses the ecliptic plane from south to north


Correct Option: A
Explanation:

The ascending node of a satellite's orbit is the point where the orbit crosses the equatorial plane from south to north.

What is the descending node of a satellite's orbit?

  1. The point where the orbit crosses the equatorial plane from north to south

  2. The point where the orbit crosses the equatorial plane from south to north

  3. The point where the orbit crosses the ecliptic plane from north to south


Correct Option: A
Explanation:

The descending node of a satellite's orbit is the point where the orbit crosses the equatorial plane from north to south.

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