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- Homework Statement
- You are a member of an Alpine Rescue Team. You must project

a box of supplies up an incline of constant slope angle a so that it reaches a

stranded skier who is a vertical distance h above the bottom of the incline.

The incline is slippery, but there is some friction present, with kinetic friction coefficient mk. Use the work–energy theorem to calculate the minimum speed you must give the box at the bottom of the incline so that it

will reach the skier. Express your answer in terms of g, h, mk, and a

- Relevant Equations
- ##W = Fscos(alpha)##

where ##s=h/sin(alpha)##

So for the work done by the kinetic friction, the displacement along the incline is ##s## as given.

What I canNOT understand is why the displacement in the y-direction is used for the work done by gravity i.e. ##W = -mgh## where ##h## is the displacement in het y-direction. This instead of the displacement along the incline

This is complete bullshit, the work done on a force was supposed to be the component along the displacement wasn't it ?

Can someone explain that to me please? Thanks in advance

What I canNOT understand is why the displacement in the y-direction is used for the work done by gravity i.e. ##W = -mgh## where ##h## is the displacement in het y-direction. This instead of the displacement along the incline

This is complete bullshit, the work done on a force was supposed to be the component along the displacement wasn't it ?

Can someone explain that to me please? Thanks in advance

**Edit: this was the answer from the book**
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