Kinetic Friction Homework Help

In summary: In this case, we can see that the coefficient of friction is much too high.In summary, a steel washer is suspended inside an empty crate from a light string attached to the top of the crate. The crate, with a mass of 154 kg, slides down a 37 degree inclined ramp. The person sitting inside the crate has a mass of 61 kg. The washer is at rest with respect to the crate when the string makes an angle of 56 degrees with the top of the crate. However, it is impossible for the crate to slide down the ramp with a coefficient of kinetic friction of 1.
  • #1
physicsquestionboi
3
0
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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  • #2
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?
 
  • #3
mfb said:
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.
 
  • #4
physicsquestionboi said:
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.
 
  • #5
haruspex said:
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
 
  • #6
physicsquestionboi said:
right nvm i have cos37 and sin37 backwards thanks
So what answer do you get now?
 
  • #7
Not everything that is given must be relevant. Finding out what is relevant and what is not is rarely practiced in homework problems, unfortunately.
physicsquestionboi said:
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.
 

What is kinetic friction?

Kinetic friction is a force that opposes the motion of an object as it slides or moves across a surface. It is caused by the microscopic roughness of the surfaces in contact, which creates resistance and slows down the movement of the object.

How is kinetic friction different from static friction?

Kinetic friction is the force that acts on an object in motion, while static friction is the force that prevents an object from moving when a force is applied to it. Static friction is typically greater than kinetic friction, as it takes more force to overcome the initial resistance and set an object in motion.

What factors affect the magnitude of kinetic friction?

The magnitude of kinetic friction is affected by the type of surfaces in contact, the force applied to the object, and the normal force (the force perpendicular to the surface). Additionally, the presence of lubricants or other substances between the surfaces can also affect the magnitude of kinetic friction.

How is kinetic friction calculated?

The magnitude of kinetic friction can be calculated using the formula Fk = μkN, where Fk is the force of kinetic friction, μk is the coefficient of kinetic friction, and N is the normal force. The coefficient of kinetic friction is a constant that depends on the type of surfaces in contact.

How can kinetic friction be reduced?

Kinetic friction can be reduced by using lubricants or other substances between the surfaces in contact. These substances create a layer that reduces the roughness and allows for smoother movement. Additionally, using smoother or more polished surfaces can also reduce the magnitude of kinetic friction.

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