physics
posted by zeph .
As Newton showed, gravity is a force that acts along the line separating two bodies and causes the two bodies to be attracted to each other (i.e. it is a central force). In this problem, assume that the planetary orbits about the Sun are circular.
a. Does the force of gravity from the Sun do work on a planet in orbit about the Sun? Why or why not?
b. What does your answer to the previous part of this problem mean for the speed of the planet as it moves about the Sun? What about its velocity?

I will be happy to critique your work , when shown any.

a horizontal force of 8.0 N is used to pull a 20N wooden box moving toward the right along a horizontal,wood surface,as shown.The diagram below shows the vector force acting representing the normal force acting on the box