# Questions tagged [friction]

The resistance a surface or object encounters when moving over another.

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### What happens to the coefficient of friction as the normal force increases?

Does the frictional force increase as the normal force increases, or does the coefficient of friction get smaller in value?
2answers
113 views

### Why does Friction act Parallel to the Surface (Microscopic Level)?

If we assume an object (blue layer) sliding towards the right across a surface (black layer). According to Newton's 3rd Law, the frictional force would act to the left (resisting the object's relative ...
0answers
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### Friction and Electric Forces [duplicate]

As I understand, friction arises from electromagnetic forces. Electric fields, at least static ones, exert conservative forces. So how is it that friction is non-conservative?
1answer
179 views

### Plastic and Iron - static and magnetic

I'm wondering if when you have a ball that is made out of plastic but has an inner core of metal. Would that ball if given friction produce static? Or would the static from the outerside of the ...
1answer
60 views

### Pure rolling and friction

If I launch a rigid cylinder (or sphere, etc.) to the surface which has a coefficient of kinetic friction $\mu_k$ and static friction $\mu_s$ with some initial velocity $v$ I think it will decelerate ...
3answers
669 views

### Dissipation and first law of thermodynamics

Consider the following situation: a certain gas is contained in a well-insulated cylinder with a well-insulated piston head. Now, in this case the piston is not frictionless. In order for the piston ...
3answers
61 views

### Friction when walking

To meet a U.S. Postal Service requirement, employees’ footwear must have a coefficient of static friction of 0.5 or more on a specified tile surface. A typical athletic shoe has a coefficient of ...
1answer
35 views

### Problem regarding friction

I require a clarification on some steps in the solution of the following problem. Problem: The coefficient of static friction between two blocks shown in figure is μ and the table is smooth.What ...
1answer
26 views

### Calculating Rolling Friction in a Lab

What would I have to measure to determine the rolling friction of a model car? Currently, I have the horizontal pulling force that the lab procedure calls for on the car, and enough data to make a ...
5answers
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8answers
35k views

### How do towels stay on hooks?

Towels (and coats) are often stored on hooks, like this: To the untrained eye, it looks like the towel will slide off from its own weight. The hook usually angles upwards slightly, but a towel does ...
1answer
239 views

### Is there any situation when oil increases friction?

I have read everywhere and tried myself to experience oil smoothening surface interfaces, thereby reducing friction. I was curious if there are instances where oil increases the friction between those ...
0answers
26 views

### Why does friction occur? [duplicate]

I'm pretty sure this is a rather stupid question but I just cannot wrap my mind around the reasoning behind friction. Now, an obvious explanation would be that since all surfaces are inherently rough,...
1answer
66 views

### how does a car move? and how do the brakes affect its velocity? [duplicate]

im doing a project that requires me to understand how cars move. from what I understand , its the friction that is creates in the tires that enables the tire to rotate, which then push the car forward....
1answer
2k views

### Why friction force is force of constraint?

My understanding about constraint force is that it is a force which limits the geometry of particle's motion. For example, situations such as the particle trapped in a track or limited in domain can ...
1answer
51 views

### A circular motion problem [closed]

A car goes on a horizontal circular road of radius $R$, the speed increasing at a constant rate $\frac{dv}{dt}=a(constant)$. The friction coefficient of the tyre is $\mu$. Find the speed at which the ...