A toy train is moving on a track from right to left. You are told that work is the dot product of force and displacement. In what direction would you apply a force so that you do the most negative work on the train? - You would apply a force that is in the left to right direction.
- You would apply a force that is in the right to left direction.
-You would apply a force that is in the down to up direction.
-You would apply a force that is in the up to the down direction.

Four point charges each having charge q are located at the corners of a square having sides of length a. find symbolic expressions for the following. (a) the total electric potential at the center of the square due to the four charges (use any variable or symbol stated above along with the following as necessary: ke.) vtotal= (b) the work required to bring a fifth charge p from infinity to the center of the square (use any variable or symbol stated above along with the following as necessary: w=