A ball is thrown straight up from the edge of the roof of a building. A second ball is dropped from the roof 2.0 s later. You may ignore air resistance. If the height of the building is 30 m, what must the initial speed be of the first ball if both balls are to hit the ground at the same time

Along the line connecting the two charges, at what distance from the charge q1 is the total electric field from the two charges zero? express your answer in terms of some or all of the variables s, q1, q2 and k =14ï€ïµ0. if your answer is difficult to enter, consider simplifying it, as it can be made relatively simple with some work.

The sun’s mass is 2.0×10^ 30 kg, its radius is 7.0×10 5 km, and it has a rotational period of approximately 28 days. if the sun should collapse into a white dwarf of radius 3.5×10 3 km, what would its period be if no mass were ejected and a sphere of uniform density can model the sun both before and after?

What is the major limitation to the light microscope?