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## Homework Statement

A constant force Fa of magnitude 85.0N is applied to a 3.0kg shoe box at angle 55.0, causing the box to move up a frictionless ramp at constant speed. How much work is done on the box by Fa when the box has moved through vertical distance h=.25m?

## Homework Equations

mgsin(angle)-Fa=0(constant speed)

mgsin(55)=Fa=24.08N

hyp=opp/sin(55)=.305m

Work=+7.35J (problably minus because the work is pointing down and displacement is up)

mgh=-7.35J

## The Attempt at a Solution

So I know that the simple way is just to use mgh. But in my homework the the box is going up, so I assume that the gravity will do negative work. But the answer is positive and they used mgh. They used Wa=-Wg and they they switched the -Wg to +Wg, and i am not sure why they did that. So was what I did correct too?