Sphere A has an excess of 10 ^ 15 electrons and sphere B has an excess of 10 ^ 13 protons. They are separated by 2.0 m. What is the force between them? A. -0.58 N
B. 0.58 N
C. 2.30 N
D. -2.30 N

25pts the diagram shows the positions of the sun, moon and earth during spring tides, when the high tides are at their highest and low tides at their lowest. what is it about these positions that causes these high and low tides?

Arunner is jogging at a steady 3.6 km/hr. when the runner is 2.9 km from the finish line, a bird begins flying from the runner to the finish line at 14.4 km/hr (4 times as fast as the runner). when the bird reaches the finish line, it turns around and flies back to the runner. even though the bird is a dodo, we will assume that it occupies only one point in space, i.e., a zero-length bird. how far does the bird travel? (b) after this first encounter, the bird then turns around and flies from the runner back to the finish line, turns around again and flies back to the runner. the bird repeats the back and forth trips until the runner reaches the finish line. how far does the bird travel from the beginning? (i.e. include the distance traveled to the first encounter)

Wavelength of 125 meters is moving at a speed of 10 m/s. what is it's frequency?