You and a Classmate Are Discussing How Much Work One $m$

Multiple Choice

You and a classmate are discussing how much work one must do to lift a box of mass $m$ a vertical distance $h$ . Your classmate argues, "You have to exert an upward force on the box at least equal in magnitude to the box's weight $m|\vec{g}|$ , and you lift the box upward a distance $h$ , so you must do work equal to $m|\vec{g}|_{t}$ . But in addition," your classmate continues, "you must increase the box's gravitational potential energy by $m|\vec{g}| h$ . Therefore, you must actually do work equal to or greater than $2 m|\vec{g}| h$ to lift the box." What amount of work do you think you need to do on the box to lift it a height $h$ ? Be prepared to defend your response. (Hint: What is the system here?)

A) Zero work
B) About $m|\vec{g}| h$ (if you move the box slowly)
C) Significantly greater than $m|\vec{g}| h$ but less than $2 m|\vec{g}| h$
D) About $2 m|\vec{g}| h$ (if you move the box slowly)
E) Significantly greater than $2 m|\vec{g}| h$