With current technologies and solar collectors on the ground, the best we can hope for is that solar cells will generate an average (day and night) power of about 230 watts/m2 . what total area would we need to cover with solar cells to supply all the power needed for the united states? give your answer in both square meters and square kilometers.

Your physics assignment is to figure out a way to use electricity to launch a small 6.0-cm-long plastic drink stirrer. you decide that you'll charge the little plastic rod by rubbing it with fur, then hold it near a long, charged wire, as shown in figure p23.56 . when you let go, the electric force of the wire on the plastic rod will shoot it away. suppose you can uniformly charge the plastic stirrer to 10 nc and that the linear charge density of the long wire is 1.0 x10-7 c/m. what is the net electric force on the plastic stirrer if the end closest to the wire is 2.0 cm away?