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.

37. Based on the data in Figure 2, how does the speed of a planet change while it moves from perihelion to aphelion and while it moves from aphelion to perihelion?

Answer and Explanation

Your Answer is

Correct Answer is C

Explanation

Look at figure 1 first, when the planet moves from perihelion to aphelion, the range of θ is 0°-180°;

When the planet moves from aphelion to perihelion , the range of θ is 180°-360°;

It can be seen from figure 2 that when θ is 0°-180°, the speed decreases;

When θ is 180° When -360°, the speed increases