Q. Greer wants to move a box to the other side of the room, which is 9 meters away. She determines that it will require 45 J of work to accomplish this. With how much force will she need to push the box in order to move it to the other side of the room?

Q. A thin, spherical, conducting shell of radius R is mounted on an isolating support and charged to a potential of -609 V. An electron is then fired directly toward the center of the shell, from point P at distance r from the center of the shell (r >> R). What initial speed v0 is needed for the electron to just reach the shell before reversing direction?