Multiple Choice Questions on Planetary Motion

Kepler's First Law states that the orbit of a planet is:

• A perfect circle.

• A straight line.

• An ellipse with the Sun at one focus.

• A parabolic curve.

Newton's Law of Universal Gravitation states that the force between two objects is proportional to:

• The sum of their masses.

• The difference in their masses.

• The product of their masses divided by the square of the distance between them.

• The distance between them.

According to Kepler's Second Law, a planet moves fastest when:

• It is farthest from the Sun.

• It is closest to the Sun.

• It is in the middle of its orbit.

• It moves at a constant speed.

What happens to a planet's orbital period if its distance from the Sun increases?

• The orbital period decreases.

• The orbital period remains the same.

• The orbital period increases.

• The orbital period becomes unpredictable.

Which of the following best describes an Astronomical Unit (AU)?

• The distance between Earth and the Moon.

• The average distance between the Sun and the Earth.

• The distance light travels in one year.

• The radius of Earth's orbit.

The force that keeps planets in orbit around the Sun is:

• Electromagnetic force.

• Gravitational force.

• Nuclear force.

• Centrifugal force.

The shape of a planet's orbit around the Sun is:

• Circular.

• Elliptical.

• Hyperbolic.

• Spiral.

What is the term for the point in a planet's orbit where it is closest to the Sun?

• Aphelion.

• Perigee.

• Perihelion.

• Apsis.

Kepler's Third Law shows the relationship between:

• Orbital speed and distance from the Sun.

• Orbital period and distance from the Sun.

• Orbital eccentricity and mass of the planet.

• Orbital shape and speed of the planet.

What would happen to a planet if the gravitational force from the Sun suddenly disappeared?

• It would continue to orbit the Sun.

• It would spiral into the Sun.

• It would move in a straight line away from its orbit.

• It would stop moving.