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Questions tagged [friction]

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

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Why friction causes energy to be lost in terms of heat when it appears to be an energy transfer mechanicsm?

For example, when we move/walk, we apply a force (via friction) on earth, and the earth in turn on us. So essentially I see it as an energy transfer as follows: Suppose I move in same direction as ...
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Why is the friction force on the bed opposite of the gravity [on hold]

So here is a simple problem and here is a diagram that I find found online. Why is the frictional force pointing downwards. I mean I get the correct answer if I follow this diagram and math checks out ...
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Rotating disk with a chain [on hold]

I need help with this problem, dont know where to start. A chain with mass $m$ stretched around a disk of radius $r$. Tension in chain is $T$. Find coefficient of friction $\mu$ if when disk is ...
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Direction of friction in non-inertial reference frame? [on hold]

A beetle is moving radially with velocity $\bf{v}$ on a disk rotating with angular velocity $\bf{w}$. The coefficient of friction between the beetle and the disk is $\mu$. Find the distance $x_0$ ...
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The speed of light and friction [closed]

In a friction free universe, light and really any object should be able to cross the universe in an instant. But without friction this wouldn't happen and time wouldn't exist. Friction=Time
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How to get multiple surface friction in diametral engine? [closed]

i assume the inicial velocity equals to acceleration and then calculate braking (v²/250u) with the weight and applied force. And i tried, on sample 2, 5 and 8, to calculate friction as an avarage ...
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1answer
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Damped oscilliations on a ball rolling in a U-shape

How do you calculate the rate of loss of energy on a ball moving in a U-shape (half sphere)? Can I simply look at the height of the ball at its peaks and measure the difference between the potential ...
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Static or Kinetic friction

When a body is acted by a force such that it begins to move. In that case which friction is applicable? Is it the static friction as that would give a minimum value of force required to move the body? ...
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Work done by friction on a oscillating disc without slipping in a circular path

Say a disc is oscillating without slipping in a circle about its stable equilibrium. I've thought of it this way: I assumed a disc is placed at, say, 3 degrees from the equilibrium. The rotation ...
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4answers
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Friction acting as an internal force

I was solving this problem in my assignment: Assuming a frictional force F acts on the block of mass m, a force -F will act on plank of mass M. Hence, the net work done by frictional force should be ...
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Does the mass affect the speed if friction is 0

A block $m_1$ strikes another stationary block $m_3$ inelastically . Another block $m_2$ is kept on $m_3$.Neglect the friction Between all contacting surfaces. Since $m_2$ is kept on $m_3$ and all the ...
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Being Frictionless, surface of contact

I hear frequently references to a smooth surface, or frictionless pulley. Can being frictionless be obtained if only one of the 2 surfaces has 0 coefficient of friction? Or it is for the contact of ...
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Why does water take a “wet” path?

Allow me to explain what I mean... ((I am asking this question in the physics section in hopes of finding a "physics" argument)) I shall make it clear what I mean by demonstrating an experiment... ...
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3answers
37 views

When does a wheel stop slipping?

I am learning about friction in rolling motion in my high school physics classes and I don't have much intuition about this. If a wheel is rolling and slipping there is a dynamic friction involved, so ...
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Damped drive oscillating systems

I am currently looking at the theory of find the viscosity of and object through damped harmonic motion, and tho it can be done there is obviously a limitation with regrades to the medium. If the ...
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2answers
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Work done by friction in a plane on a ball

An inclined plane has a rough and smooth surface which are of equal length. A ball is kept at rest at a height $h$ and is then rolled on the surface of the inclined plane. My question is that ...
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Is the Euler-Eytelwein equation also applicable for sliding friction?

Is the Euler-Eytelwein equation also applicable for sliding friction? Does this hold true if you just replace the coefficient of static friction with the one of sliding friction? I'm working on a ...
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2answers
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Work done by friction when object is rolling WITH slipping [closed]

So if I have an object that is rolling with slipping like a bowling ball, if I use W=F•dr definition, then work done by friction has to be negative. But if I use the W=τ•dθ definition, then work is ...
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How is the simple damper equation derived?

I know the spring is modeled as $F_{\text{elastic}} = k\cdot x$ when the displacements are small since this is empirically based, but what happens with $F_{\text{damping}}=c\cdot\dot{x}$? It is the ...
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2answers
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Does the friction between the tires of a bicycle and the ground increase as speed increases?

My question is quite simple "Does the friction between the tires of a bicycle and the ground increase as speed increases?" I know that drag does increase as velocity increases, but what happens to the ...
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2answers
102 views

Harmonic motion with friction [closed]

Consider an undamped mass and spring system with friction. The friction is not proportional to the velocity of the mass. If we solve the corresponding differential equation,the spring will oscillate ...
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Derivation of friction in interleaved phonebooks

Trying to understand the simple model in https://arxiv.org/abs/1508.03290, describing the friction between the pages of two interleaved phonebooks. Specifically I don't see how to get Eq. 1. Here's ...
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What does the term “no slipping” mean in mechanics?

Say, I have two blocks. One block is on top of the other. Suppose friction is present everywhere. What is the condition for no slipping?
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2answers
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What is the force of friction on the body? [duplicate]

This might seem like a stupid question, but my instructor could not give a straightforward answer. If a body is kept in contact with a completely vertical surface i.e. right angle to the ground, and ...
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1answer
39 views

Force exerted by a motor, velocity, and friction

Some motor make an object move on a surface very slowly. One can write at steady state : $F_{motor}-F_{friction}=0$. The friction is supposed to come from the surface so : $F_{motor}-\mu_s m g=0$ with ...
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1answer
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Diffusion 2D on a surface : diffusion coefficient and surface friction

We have a particle that is diffusing actively (meaning that the source of energy is a motor; the diffusion is like a Brownian motion, the only difference is that the diffusion coefficient is much ...
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1answer
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Calculate stroke force and angle for a ball rolling on a surface to reach a destination position (optimal golf putt)

I'm trying to find an algorithm which calculates the optimal golf putt (angle, force) given a 3D surface (obtained through Poisson reconstruction), start and destination position (hole). I guess that ...
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2answers
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Why does not the static friction produce heat and waste energy?

I have asked this question wrt this question. So I want to ask the static friction opposing not the motion of the field just helps the field to get the energy back so the work now why does not the ...
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Can kinetic and static friction act at the same time for this object rotating inside an accelerating cylinder?

Let say we have a rotating cylinder with constant angular velocity (w). On the inside wall there is an object which is rotating with the cylinder without sliding. And we know that the static friction ...
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2answers
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Frictional force on smooth surface [closed]

While walking on ice , one should take small steps to avoid slipping. This is because smaller steps ensure $A)$ smaller friction $B)$ larger friction $C)$ larger Normal force $D)$ smaller Normal ...
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2answers
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Work done by static friction? Conveyor belt vs frictionless lego pieces

Theoretically (I thought) static friction does no work. Practically, this answer says it does and it's using a conveyor belt as an example. My question here is: In the conveyor belt case, are the ...
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1answer
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Where does the heat energy dissipated by friction come from?

I know that when a force is exerted on an object by another one which causes it to move, work is performed. As a result energy is transferred to the object by the force from other object. But ...
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2answers
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Work done by friction in this Case

So there is an elevator going down with a constant and the block does not slip on the wedge. We have to find the work done by friction in time t. So the answer given is $-mgvt\sin^2\theta$. What I ...
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1answer
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Does a wheel deform more when its rolling or when its still?

With no need to get into the details (although the article is linked below if you wish to read it), the coefficient of rolling friction is a measurement of how much the bottom of a wheel deforms when ...
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1answer
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Why should the friction between two disks be zero when there velocity is same? [duplicate]

In this video here, Walter Lewin mentions two discs of different radius $r_1$ and $r_2$, of the same density, where the first disk is initially rotating, while the second is at rest. In the videos ...
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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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Determining direction of friction in 3d problems

How to determine the direction of friction in complex problems? I can determine direction of friction in 2d problems which involve wedges and pulleys. But when it comes to 3d problems i always get ...
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How does frictional force push when we walk?

Friction is due to the attractive force between the body and the surface so how does it push us forward when we walk or in a bicycle
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The motion of an object in a slant surface against friction

if I take to surfaces slant at the same degree wouldn't there coefficient of friction be different depending on the nature of the surfaces
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How does friction facilitate charge redistribution?

We know that when Amber is rubbed with wool, the surfaces that are in contact, taken together, have the charges redistributed in accordance with the Law of Conservation of Charge. How does friction ...
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1answer
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Incline Plane problem [duplicate]

If a block is at rest on the incline plane at an angle of 30 degrees, would the maximum frictional force that would allow the block to stay in place be calculated using 30 degrees, OR would we have to ...
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2answers
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Incline Plane - Coefficient of friction and kinetic friction

A block of mass 90 kg sits on a slope with an angle of inclination 12° above the horizontal. The coefficients of friction between the block and the slope are µk = 0.03 and µs = 0.2. a. What is the ...
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Teflon (PTFE) against another teflon [closed]

Would teflon sleeve spinning againts teflon bushing create so much friction that it would just break? I have a teflon bushing spinning againts metal sleeve, and it is the original design, which works. ...
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Speed of an object when moved by two belts

There is a transport drive with a top belt driven by a motor M1 and a bottom belt driven by a motor M2. Between the belts there is an object which borders with each of the belts equally and due to ...
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1answer
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How exactly does does friction rotate a wheel?

All I know is that the wheel pushes the ground and the ground pushes back (friction). Pls can anyone elaborate on this process?
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1answer
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Does static friction only depend on the forces acting on the axis perpedicular to the plane where an object is located?

Suppose I have a vehicle with 4 wheels all connected to motors which is hauling a set of wagons. Suppose also that: The contact between wheels and ground plane is uniform. The weight of each wehicle ...
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2answers
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Reason for neglecting frictional force in a particular type of Motion

A thin inelastic string is tightly wound on a cylinder. One of the ends of the string is attached to the above surface. Initially the whole system (string +cylinder) is held near the surface. When it ...
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Couple or torque

In the solution of Problem 527, over here, A homogeneous cylinder 3 m in diameter and weighing 30 kN is resting on two inclined planes as shown in Fig. P-527. If the angle of friction is 15° for ...
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Sliding to Rolling

In a problem where a sphere is initially sliding and then begins to roll after having travelled some distance. The thing that confused me is that the work done by friction on the sphere is not simply ...