a. An escalator carries you from one level to the next in an airport terminal. The upper level is \(4.5 \mathrm{~m}\) above the lower level, and the length of the escalator is \(7.0 \mathrm{~m}\). How much work does the up escalator do on you when you ride it from the lower level to the upper level?

b. How much work does the down escalator do on you when you ride it from the upper level to the lower level?