Calculate force of friction using tension & angles

AI Thread Summary
To calculate the force of friction for a 60 kg crate being dragged with a tension of 20N at a 70-degree angle, the normal force (Fn) is derived from the gravitational force (Fg) adjusted for the angle. The gravitational force is calculated as 588N, and the normal force is found to be 201N using Fn = Fg * cos(70). The force of friction can be determined by considering the vertical components of the forces acting on the crate, leading to the equation |Ff| = |Fg| - |T|sin(70). The coefficient of friction can then be calculated using the relationship ffr = U * Fn. This discussion emphasizes the importance of correctly analyzing the forces involved in the scenario.
bhangu23
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Homework Statement


A 60 kg crate is being steadily dragged along the floor by a rope, which makes an angle of 70 degress with the horizontal. If the tension in the rope is 20N:
What is the force of friction?
What is the coefficient of friction?

Homework Equations



ffr=Ufn
ffr=Umgcos0


The Attempt at a Solution



i know that
fg=mg
= 60(9.8)
=588N

and
Fn= fgcos70
=588cos70
=201N

i don't knwo what to do from there
 
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anyone?
 
I'm not sure why your normal force is Fg*cos(70). From my diagram, I get the force of friction |Ff| = |Fg| - |T|sin(70) where T is the tension.
 

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