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.

36. Consider a planet as it travels from θ = 0° to θ = 359° in an orbit with a semimajor axis of 1.5 x 108 km and an eccentricity of 0.10. Based on the data in Figure 2, how many times does the planet have a speed of 30 km/sec as it travels between those 2 angles?

Answer and Explanation

Your Answer is

Correct Answer is G

Explanation

Look at the first picture of figure 2, and pay attention to the solid line inside (eccentricity is 0.10), the solid line passes through the point whose ordinate speed is 30 km/sec twice