Why is Friction Squeaky?

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In summary: So if you have a drawer that is made of plastic and you try to pull it out and the plastic squeaks, it's because the static friction of the two surfaces is greater than the sliding friction.
  • #1
Why is it that when you pull out a cheap plastic drawer, there is sometimes a squeak that makes your ears bleed? (exaggerated.)

I know it has to do with friction but why does it squeak? Or rather, what causes the squeak?

If I run my finger down a surface, there is no squeak. Even if there is it's not nearly as high-pitched...

What's the difference between the two situations?
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  • #2
Interesting. I'm going to hazard a guess that should be similarily true of the squeak a bow causes a fiddle string.

Becuase you have two similar materials--plastic drawer and plastic case the two materials tend to bind to each other.

The binding and break-away as you continue to pull the drawer sets up waves at the bind/break-away frequency. Binding occurs pulling the cabinet lip with it, it breaks-away oscillating in the opposite direction only to rebind when the velocites are a closest match. So I think it's the cabinet that vibrates, not the drawer. Maybe we should consult violin rosin manufactures about this.
  • #3
Wow I didn't expect such an answer for such a simple question... nice :)

So may I ask, what is it that causes the binding of the drawer, and the cabinet?
  • #4
BL4CKCR4Y0NS said:
Wow I didn't expect such an answer for such a simple question... nice :)

So may I ask, what is it that causes the binding of the drawer, and the cabinet?

Remember, I'm just guessing about this. But if you were to visit the mechanical engineering folder and ask about similar vs. dissimilar materials in bearing surfaces, you might get a more informed answer. For instance, it may only be that bearing and journal should be dissimilar materials if they are metal, and I'm all wrong about plastics. Or it could just be that one surface just has to be a harder metal than the other. I'm not a materials expert, so I don't know much about it.

This is also about simple friction which is a more basic physics exercise than anything, unless you look at the microscopic level. The sliding friction between two surfaces is less than the static friction.
  • #5

Friction is the force that resists the motion of two surfaces in contact with each other. When you pull out a cheap plastic drawer, the friction between the drawer and the surface it is resting on is what causes the squeak. This is because the surfaces are rough and have microscopic irregularities that create resistance when they come into contact with each other. The higher the friction, the louder and more pronounced the squeak will be.

In the case of running your finger down a smooth surface, there is still friction present, but it is much lower due to the smoother surfaces. This results in a lower-pitched or non-existent squeak.

Additionally, the materials of the surfaces can also play a role in the squeakiness. Cheap plastic may be more likely to produce a squeak compared to a smoother material like metal or wood.

Overall, the squeakiness is a result of the interaction between the rough surfaces and the force of friction. The higher the friction, the more pronounced the squeak will be.

1. Why do objects make a squeaking sound when they rub against each other?

Friction is caused by the resistance between two surfaces when they are in contact and moving against each other. When this happens, the surfaces vibrate and create sound waves, resulting in a squeaking sound.

2. What makes certain objects squeak more than others?

The amount of friction between two surfaces depends on various factors such as the materials of the surfaces, the amount of force applied, and the smoothness of the surfaces. Objects that are rough or have a higher coefficient of friction tend to make more squeaking sounds when rubbed against each other.

3. Can lubricants reduce squeaking caused by friction?

Yes, lubricants can reduce friction between two surfaces, making them glide against each other more smoothly. This reduces the amount of vibration and sound produced, resulting in less squeaking.

4. Why do some surfaces squeak more when they are dry?

Dry surfaces have a higher coefficient of friction, meaning they have more resistance when rubbed against each other. This results in more vibration and sound, causing the surfaces to squeak more.

5. Can the temperature affect the amount of friction and squeaking?

Yes, temperature can affect friction and squeaking. When the temperature is high, the surfaces become smoother, reducing the amount of friction and squeaking. On the other hand, lower temperatures can make surfaces rougher, resulting in more friction and squeaking.

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