Passage II

The shape of a planet's orbit around a star is elliptical. Kepler's third law of motion relates the planet's orbital period (the time the planet takes to complete one orbit) to the ellipse's semimajor axis, , (see Figure 1) and the star's mass. Figure 2 contains a graph of the orbital period versus for 6 of the planets that orbit the Sun. The average orbital speeds of these planets are plotted versus in Figure 3.

Kepler's third law also describes a moon's orbit around a planet. Figure 4 contains graphs of the orbital period versus a for moons orbiting hypothetical planets of various masses.

(Note: In Figures 2-4, 1 AU = 1.5 x 108 km, the average distance from Earth to the Sun, and periods are given in multiples of Earth days or years.)

(Note: In Figure 4, moons' masses are assumed to be insignificant compared to the masses of planets they orbit.)

11. The planets in Figure 3, ranked from smallest to largest according to their masses, are Mercury, Mars, Venus, Earth, Saturn, and Jupiter. Does this information and Figure 3 support the hypothesis that a planet's mass and its orbital speed are related?

Answer and Explanation

Your Answer is

Correct Answer is D

Explanation

Figure 3 clearly shows that the orbital speed is related to the length of the semimajor axis, but it is not related to the mass, so choose No. For example, Jupiter has the highest quality, but Jupiter's speed is not the fastest, nor is it the slowest