Passage VII
Planets revolve around the Sun in elliptical orbits, as shown in Figure 1.
The eccentricity of an elongated the ellipse describes its elongation; the more elongated the ellipse, the greater its eccentricity. The semimajor axis is half the length of the ellipse.
Perihelion (Angle θ = 0°) is the point on the orbit closest to the Sun; aphelion (θ = 180°) is the point on the orbit farthest the Sun. The speed of a planet varies with θ.The speed of a planet versus θ is shown in Figure 2 for orbits with various eccentricities and semimajor axes.
39. Based on the data in Figure 2, the orbital speed of a planet will most likely remain constant if the eccentricity of the planet's orbit is:
Your Answer is
Correct Answer is A
Explanation
Observing any of the pictures in figure 2, it is found that the smaller the eccentricity is, the less the speed changes when the planet moves on the entire orbit. Therefore, it is speculated that when the eccentricity is 0, the speed remains constant< /p>