Kepler's Third Law of Planetary Motion

The video tutorial covers Kepler's third law of planetary motion, explaining that the square of a planet's orbital period is proportional to the cube of the semi-major axis of its orbit. The teacher clarifies the law, discusses constants involved, and uses data from the solar system to illustrate the concept. The video concludes with a graph showing the relationship between orbital period squared and semi-major axis cubed, emphasizing the use of specific units to simplify calculations.

What does Kepler's Third Law state about the relationship between a planet's orbital period and its semi-major axis?

• The orbital period is inversely proportional to the semi-major axis.

• The square of the orbital period is proportional to the cube of the semi-major axis.

• The square of the semi-major axis is proportional to the cube of the orbital period.

• The orbital period is directly proportional to the semi-major axis.

What is the semi-major axis in the context of an elliptical orbit?

• The shortest distance from the center of the ellipse to the curve.

• The distance from the center of the ellipse to one of its foci.

• The average distance from the center of the ellipse to the curve.

• The longest distance from the center of the ellipse to the curve.

In Kepler's Third Law, what is the 'primary' object in the solar system?

• The Earth

• The Moon

• The Sun

• A planet

What unit is used to measure the semi-major axis in the solar system?

• Light years

• Parsecs

• Kilometers

• Astronomical units

Why do all planets have roughly the same value for the ratio of orbital period squared to semi-major axis cubed?

• Due to the alignment of the planets.

• Due to the use of Earth-based units for measurement.

• Because of the gravitational pull of the Sun.

• Because all planets have the same mass.