3.2 Kepler's Laws

Kepler's first law states that planets can orbit a star (i.e. the sun) in the shape of a

• circle

• ellipse

• rectangle

• pentagon

True or false? Kepler's Laws only apply to planets orbiting a star.

• True

• False

True or False? In an orbit around a star, a planet will always be travelling at the same speed.

• True

• False

When will an orbiting planet travel at its greatest speed?

• The planet's path is close to the star it is orbiting.

• The planet's path is far from the star it is orbiting.

• The planet is always travelling at its greatest speed.

• The planet is never travelling at its greatest speed.

When considering a planet orbiting a star, the star is said to be

• the center of rotation

• a focus of the orbiting path

• the focus of the orbiting path

• the center of the universe

Kepler's third law states that K = R³/T². Which of the following is true?

• R is the same no matter where a planet is in its orbit.

• R is different depending on where a planet is in its orbit, so we cannot use Kepler's third law.

• R is different depending on where a planet is in its orbit, so we take the average radius of orbit when using Kepler's third law.

• R represents the period of the orbit.

Which of the following is true?

• Every focus has its own Kepler constant, which impacts how objects will orbit around it.

• Every focus has the same Kepler constant, which allows us to calculate how objects will orbit around any focus.

• Every focus has its own Kepler constant, which impacts how the focus orbits around different objects.

• Every focus has the same Kepler constant, which allows us to calculate how each focus will orbit around different objects.

Select all that apply. Which statements are true about a geostationary orbit?

• If a satellite is in a geostationary orbit relative to Earth, a stationary person on Earth will always be able to see the satellite no matter what time of day it is.

• If a satellite is in a geostationary orbit relative to Earth, it will orbit the Earth once every 24 hours.

• If a satellite is in a geostationary orbit relative to Earth, a stationary person on Earth will be "directly under" the satellite once per day.

• If a satellite is in a geostationary orbit relative to Earth, it will orbit the Earth once every 365 days.

Suppose Kepler's constant for planet X is K = 14.72 * 10¹⁴ m³/s². If a satellite takes 5.37 * 10⁷ s to orbit Planet X, what is its average orbital radius?

• 4.24 * 10³⁰ m

• 1.62 * 10³⁰ m

• 4.24 * 10 ¹⁰ m

• 1.62 * 10¹⁰ m

Suppose Kepler's constant for planet X is K = 14.72 * 10¹⁴ m³/s². A satellite orbits planet X with an orbital radius of 2.82 * 10⁶ m. How long does it take for the satellite to orbit planet X?

• 1.52 * 10⁴ s

• 1.23 * 10² s

• 1.52 * 10² s

• 1.23 * 10⁴ s