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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?