Q. At each point on the surface of the cube the electric field is parallel to the z axis. The length of each edge of the cube is 3.9 m. On the top face of the cube the electric field is in the negative z direction and has a magnitude of 43 N/C magnitude. On the bottom face of the cube the field is in the positive z direction and has a magnitude of 19 N/C. Determine the net charge (in nC) contained within the cube.
Q. A lighthouse that rises 49 {rm ft} above the surface of the water sits on a rocky cliff that extends 19 {rm ft} from its base. A sailor on the deck of a ship sights the top of the lighthouse at an angle of 30.0 above the horizontal.
If the sailor's eye level is 14 {rm ft} above the water, how far is the ship from the rocks?