Effect of Tangential and Normal Forces on Orbital Velocity of Planets

[Numnum]

Homework Statement

What effect will the tangential component of force have on the velocity of the planet?
What effect will the normal component of force have on the velocity of the planet?

Homework Equations

The Attempt at a Solution

1. Since it is parallel to the direction of velocity, maybe it speeds it up/slows it down depending on the location of the planet on the ellipse?

2. No effect since it is perpendicular to the direction of motion.

I'm not really sure if I am right.

 

[Simon Bridge]

What is the direction of the force that holds a planet in it's orbit?

Note: velocity is a vector.