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bakin

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## Homework Statement

You drag a trunk of mass m across a level floor using a massless rope that makes an angle with the horizontal (figure below). Given a kinetic-friction coefficient (mu).

Find the minimum force needed to move the trunk with constant speed.

## Homework Equations

F=ma

Fk=µk(Fn)

## The Attempt at a Solution

What's really getting me is that the site says the answer

*doesn't*depend on theta.

I found the normal force being Fn=mg-FsinΘ

the total friction force being µk(mg-FsinΘ)

For the force equation,

F=ma

F=0

FcosΘ=µk(mg-FsinΘ)

Solving for F, I came up with:

F= (-µkmg)/(µksinΘ-cosΘ)

Again, says no theta in the answer though. Any pointers?