Questions tagged [friction]

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

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3answers
11k views

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?
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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 ...
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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?
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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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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5answers
3k views

Finding the acceleration of a mass/pulley system without knowing the direction of the displacement

I have the following question: I noticed that if I solve for the acceleration assuming that the acceleration is occuring to the left, I get the equation: $\displaystyle a = \frac{m_3g-\mu_km_1gcos\...
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1answer
62 views

How long would “artificial gravity” remain on an O'Neill cylinder without power? [closed]

An O'Neill Cylinder (as defined by O'Neill, per Wikipedia) has two cylinders which are both "5 miles (8.0 km) in diameter and 20 miles (32 km) long, connected at each end by a rod via a bearing system"...
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208 views

Uniform Circular Motion w/ Tension and Friction

So I had a problem today which I couldn't make any sense of. I don't have access to it at the moment but this is a pretty accurate approximation. Basically, a mass (m) is swinging horizontally on ...
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1answer
36 views

Rubber-Rubber friction

We all know rubber is known to have a high friction coefficient, and it's quite difficult to drag a block of it across a surface. What happens when two blocks of flexible rubber are dragged against ...
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1answer
562 views

Contact force between two boxes when static frictional force>external force

A question that my friend asked me but I can't figure out why the answer is C. Won't the block not move and net resultant force = -4.525? I haven't learnt about static and kinetic friction and am ...
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1answer
25 views

Finding acceleration of a stacked box system, when they are not relative [closed]

Two boxes are stacked, box $A$ is placed on a horizontal surface with no friction, box $B$ is placed on box $A$ with unknown coefficient friction between the two. Box $A$ does not slide relative to ...
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1answer
583 views

Circular motion, kinetic friction and tension

Hi: I've read this post: Uniform Circular Motion w/ Tension and Friction and helped me a lot. I have a similar problem: At one end of the rope ($R = 1 m$) is tied a mass ($m = 3 kg$) and the ...
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479 views

Static friction free body diagram on a flat plane

Do you include static friction on a free body diagram for a static box on a flat surface? Or do you just include Force of gravity and Normal force? We know when the box is moving there is Frictional ...
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1answer
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How can a rope's tension be at a maximum as a body is about to move up a slope in the rope's direction? [closed]

Note: I do NOT need this exercise's answer. I have no problem working the math out and noticing the truth of my title. A box of mass 0.5 kg is placed on a plane which is inclined at an angle of 40 ...
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1answer
65 views

Friction in pulleys

The moment equation of a pulley with a rope applying tension on both sides is as follows: $$I\alpha = f + T_1R - T_2R$$ ( $I$ - moment of inertia; $\alpha$ - angular acceleration; $f$ - friction ...
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4answers
202 views

Friction while Rolling Without Slipping

This is an excerpt from an elementary Physics textbook ("Fundamentals of Physics" by Halliday), which describes what happens when a wheel that is "rolling without slippging" doesn't have a constant ...
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Problem with Impure Rolling [closed]

Can someone explain what happens in the below situation Looking at it from the planks frame of reference: The cylinder Velocity= 20(-i) Net friction force on cylinder f=2umg(i) (here u=1/2) ...
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4answers
1k views

In which direction does the friction act in a circular motion?

I want to know how a body moves on a circular track. Suppose a car enters a circular path. If I don't turn my steering wheel, then the car would travel in straight line and perpendicular to the radius ...
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1answer
461 views

Graph explanation for force and friction

Question: A block of mass $m$ is placed on an inclined plane with angle of inclination $\theta$. Let $N$, $f_L$ and $F$ respectively represent the normal reaction, limiting force of friction and the ...
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2answers
470 views

Motion of an object spiraling outwards on a rotating disk with friction

I recently came across the following problem: A spinning disk has an object initially located at radius R. The object is moving with the same angular velocity as the disk (which I will call ω). ...
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3answers
789 views

Is there such thing as a critical value for the coefficient of friction?

Is it possible for coefficient of friction to be so high that no matter what force is applied to an object, the object will never move? For example, if I have an incline and a box on the incline ...
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0answers
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Factors effecting the time period of Euler's disk [closed]

I wish to carry out research on the factors effecting the time period of a spinning Euler's disk. Do factors like friction coefficient of the base or concavity of the base effect the disk? If not, ...
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0answers
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Turbulent flow in a pipe - how to compute the friction coefficient $\lambda$

Consider a pipe of diameter $D = 0.01$ m and Length $L = 1.0$ m represented in the figure underneath. At the in- and outlet, the pipe cross-section converges, respectively diverges smoothly. We will ...
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1answer
933 views

Blocks and pulleys problem with friction - the condition for sliding

I encountered a problem with blocks and pulleys, which I'm not sure about. The diagrams I've drawn are given below. We need to find the minimal mass $M$ of the block $3$, such that block $1$ starts to ...
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5answers
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What is the cause of rolling friction? & why is it less than sliding friction?

Rolling friction is the resistance to motion experienced by a body when it rolls upon another. It is much less than sliding friction for same pair of bodies. When one body rolls upon another, there is ...
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4answers
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Understanding the notion of lose or win of angular momentum in accretion disk

Here is below a slide of one of my lecture in planetology : I understand well the fact that ring A will be slow down by friction with ring B since ring B is rotating slower and the inverse process (...
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1answer
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What are the forces acting on this car?

i found a cool website that explains sort of like the forces acting on the car and they seem to explain the process behind it. the website gives a free body diagram but the problem is that it doesn't ...
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0answers
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How does different shuffleboard powder affect the disks' speed

I do know there is friction and surface tension involved here but am not sure on how exactly does different kinds of shuffleboard powder affect the disks' speed. So taking into the account the ...
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6answers
740 views

Does rolling friction increase speed of a wheel?

I know there are a lot of questions about rolling friction, but I couldn't find any that addressed my specific problem. Note the following picture where the wheel rotates clockwise. The rolling ...
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2answers
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Explaining friction using Hamiltonian mechanics

I have heard the opinion that it is a good assumption that microscopically all forces are actually conservative so in principle all classical mechanics problems could be solved using Lagrangian / ...
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1answer
3k views

Does Mass affect Speed of a Sliding Object With friction?

Sorry if this has been already asked, but I've been looking around google for a while and couldn't find an answer suitable. I'm a beginning physics student so pardon the dumb question. Let's say we ...
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4answers
965 views

Why we can't write in air? [closed]

Why we always require a surface to write something? Why we can't write in air? I think that it is due to friction but I am not sure about it. Edit As per helpful comments and responses, I think ...
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3answers
86 views

Is friction enabling relative motion between bodies in contact?

If the surface object B is placed on is frictionless, on applying a force F on object A, friction will act on object A opposite to the direction of the force applied (opposite to the direction of its ...
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1answer
435 views

Understanding role of friction in block on block problems

Consider two blocks stacked on top of one another. There is friction between the blocks but there is no friction between the lower block and the table. So the only frictional force that tends to ...
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2answers
751 views

How to find the initial push force needed for a rolling system?

Assume I have a system 4000 lbs with 4 casters. The static coefficient of friction is 0.7 to the floor. Do I need to provide 2800 lbs as initial pushing force in order to make the system to roll? (...
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1answer
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Is there a reference frame in which the static friction from rolling does positive work?

I am worried this will be deleted as a duplicate question, so I will try to be extra clear what I am asking: In some reference frames, static friction can do positive work. If you have a crate in the ...
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2answers
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Force to start moving a car

I have 2 related questions, the second one is more engineering than physics, but it relies on the first. Does it take more force to get a car to start moving than to accelerate it the same amount ...
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1answer
74 views

Are there any formulas that calculate the stopping distance of a car on different surfaces that include deceleration?

I already found the formula $d = v^2/2\mu g$ where '$v$' is for velocity, '$\mu$' is for the coefficient of friction between the tires and the road surface, and '$g$' is the acceleration of gravity. ...
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4answers
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Ball rolling into a bowl - where is its maximum KE (speed)… given there is friction. See diagram

Please examine this diagram and answer the apparently trivial questions. I am particularly interested in reasoned answers for part (a)(ii) - where is the maximum Kinetic energy? I say it is at B (as ...
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0answers
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How to calculate the viscous damping coefficient of a viscous layer between an inner sphere and an enclosing outer sphere?

In this article by Rahn and Barba, a flat-spin transition manoeuvre is investigated. For this it is assumed that a rigid spacecraft contains a spherical, dissipative fuel slug of inertia $\boldsymbol{...
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8answers
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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 ...
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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 ...
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0answers
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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,...
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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....
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1answer
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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 ...
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1answer
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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 ...