A suitcase is hanging straight down from your hand as you
Chapter 6, Problem 6.26(choose chapter or problem)
A suitcase is hanging straight down from your hand as you ride an escalator. Your hand exerts a force on the suitcase, and this force does work. This work is (a) positive when you ride up and negative when you ride down, (b) negative when you ride up and positive when you ride down, (c) positive when you ride up or down, (d) negative when you ride up or down.
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