Stretch or shrink the velocity vector so, when you click Play, the orbit is circular. Use the formula you derived in item 8 to determine the speed that will result in a circular orbit when the Sun is 2.0 Solar masses.

Your answer is 1.5 hope i  

Answer(a)   the matererials that are in contact, the two materials and the nature of their surfaces/// (b)/// the force pushing the two surfaces together, pushing the surfaces together causes the more of the asperities to come together and increases the surface area in contact with each other