Coefficient of Kinetic Friction for crate

[Tylersaurus]

Homework Statement

A 1500 N crate is being pushed across a level floor at a constant speed by a force F of 700 N at an angle of 20° below the horizontal.

What is the coefficient of kinetic friction between the crate and the floor?

Homework Equations

f=mu(n)

The Attempt at a Solution

I tried 700cos20/1500 + 1500sin20 using the horizontal component of the applied force divided by the normal force, which was mg plus the vertical component of the applied force, but it didn't work, obviously. Any suggestions?

 

[learningphysics]

Your description seems right, but your numbers don't look right. The vertical component of the applied force is 700sin20... not 1500sin20

 

[PhanthomJay]

Homework Statement

A 1500 N crate is being pushed across a level floor at a constant speed by a force F of 700 N at an angle of 20° below the horizontal.

What is the coefficient of kinetic friction between the crate and the floor?

Homework Equations

f=mu(n)

The Attempt at a Solution

I tried 700cos20/1500 + 1500sin20 using the horizontal component of the applied force divided by the normal force, which was mg plus the vertical component of the applied force, but it didn't work, obviously. Any suggestions?

I'm not sure of your equations, but the force is applied below the horizontal; you seem to have assumed when calculating the normal force that the applied force is above the horizontal.

 

[learningphysics]

I'm not sure of your equations, but the force is applied below the horizontal; you seem to have assumed when calculating the normal force that the applied force is above the horizontal.

no, he assumed it was below the horizontal. He just used 1500 + 1500sin20 for the normal force, instead of 1500 + 700sin20.

 

[Tylersaurus]

Yeah, I got that later. Thanks, though.