The figure below shows a planet traveling in a counterclockwise direction on an elliptical path around a star located at one focus of the ellipse. When the planet is at point A,
A) its speed is constant.
B) its speed is increasing.
C) its speed is decreasing.
D) its speed is a maximum.
E) its speed is a minimum.

Question

The figure below shows a planet traveling in a counterclockwise direction on an elliptical path around a star located at one focus of the ellipse. When the planet is at point A, 
A) its speed is constant. 
B) its speed is increasing. 
C) its speed is decreasing. 
D) its speed is a maximum. 
E) its speed is a minimum.

Quizplus · Accepted Answer

According to Kepler's Second Law, a planet travels faster when it is closer to the star and slower when it is farther away. Point A is closer to the star than point B, which means that the planet's speed at point A is slower than its speed at point B. Therefore, its speed is decreasing at point A.

The Figure Below Shows a Planet Traveling in a Counterclockwise