Suppose you have a friend who has a part-time job translating computer maintenance training materials from Japanese into English. A section of a manual for an inkjet printer is missing, and an important derivation is needed. The printer works by steering drops with charge and mass between two parallel surfaces where there is a uniform electric field that deflects them the appropriate amount (see the figure). The field extends over the length and width . The reader of the manual must know the minimum speed of the drop if it is to make it through the electric field region without hitting either of the plates.