# Kinetic Friction Homework Help

A steel washer is suspended inside an empty crate from a light string attached to the top of the crate. The crate slides down a long ramp that is inclined at an angle of 37 above the horizontal. The crate has mass 154 kg. You are sitting inside the crate; your mass is 61 kg. As the crate is sliding down the ramp, you find the washer is at rest with respect to the crate when the string makes an angle of 56 with the top of the crate. What is the coefficient of kinetic friction between the ramp and the crate?

I got roughtly 1.22 but my answer did not involve the masses so I am a little sus.

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mfb
Mentor
With that coefficient of friction the crate would not slide down the ramp.

It is impossible to tell what went wrong if you don't show your work (that's what the homework template was for, but you can also edit it into your post now).

Do you expect the masses to matter?

With that coefficient of friction the crate would not slide down the ramp.

It is impossible to tell what went wrong if you don't show your work (that's what the homework template was for, but you can also edit it into your post now).

Do you expect the masses to matter?
My work was very sloppy and would not really make sense, and yes it would slide down the ramp, check your calculations. I also would not think that the masses would matter, but they were given in the problem and I am not a master of physics, so I am not sure.

haruspex
Homework Helper
Gold Member
yes it would slide down the ramp, check your calculations.
Check yours. E.g. with a coefficient of 1 it would require an angle greater than 45 degrees to slide down.

Check yours. E.g. with a coefficient of 1 it would require an angle greater than 45 degrees to slide down.
right nvm i have cos37 and sin37 backwards thanks fool

haruspex
Homework Helper
Gold Member
right nvm i have cos37 and sin37 backwards thanks
So what answer do you get now?

mfb
Mentor
Not everything that is given must be relevant. Finding out what is relevant and what is not is rarely practiced in homework problems, unfortunately.
and yes it would slide down the ramp, check your calculations.
I didn't need a calculation to see that it would not, using the same argument as haruspex.
Checking answers for plausibility is often useful.