Planets go around the sun in elliptical orbits. The highly exaggerated diagram below shows a portion of such an orbit and the force on the planet at one position along that orbit. The planet is moving to the right. F|| and $F_{\perp}$ are the components of the force parallel (tangential) and perpendicular (normal) to the orbit. The work they do is W|| and $W_{\perp}$ . At the position shown:
A)W|| slows the planet down; $W_{\perp}$ speeds it up.
B)W|| slows the planet down; $W_{\perp}$ does no work on it.
C)W|| speeds the planet up; $W_{\perp}$ does no work on it.
D)W|| speeds the planet up; $W_{\perp}$ slows it down.
E)W|| does no work on it; $W_{\perp}$ speeds the planet up.

Question

Planets go around the sun in elliptical orbits. The highly exaggerated diagram below shows a portion of such an orbit and the force on the planet at one position along that orbit. The planet is moving to the right. F|| and $F_{\perp}$ are the components of the force parallel (tangential) and perpendicular (normal) to the orbit. The work they do is W|| and $W_{\perp}$ . At the position shown: 
A)W|| slows the planet down; $W_{\perp}$ speeds it up. 
B)W|| slows the planet down; $W_{\perp}$ does no work on it. 
C)W|| speeds the planet up; $W_{\perp}$ does no work on it. 
D)W|| speeds the planet up; $W_{\perp}$ slows it down. 
E)W|| does no work on it; $W_{\perp}$ speeds the planet up.

Quizplus · Accepted Answer

The Answer of Planets go around the sun in elliptical orbits. The highly exaggerated diagram below shows a portion of such an orbit and the force on the planet at one position along that orbit. The planet is moving to the right. F|| and $F_{\perp}$ are the components of the force parallel (tangential) and perpendicular (normal) to the orbit. The work they do is W|| and $W_{\perp}$ . At the position shown: 
A)W|| slows the planet down; $W_{\perp}$ speeds it up. 
B)W|| slows the planet down; $W_{\perp}$ does no work on it. 
C)W|| speeds the planet up; $W_{\perp}$ does no work on it. 
D)W|| speeds the planet up; $W_{\perp}$ slows it down. 
E)W|| does no work on it; $W_{\perp}$ speeds the planet up.

Planets Go Around the Sun in Elliptical Orbits F⊥F_{\perp}F⊥​ Are the Components of the Force Parallel (Tangential) and Perpendicular

Planets Go Around the Sun in Elliptical Orbits $F_{\perp}$ Are the Components of the Force Parallel (Tangential) and Perpendicular