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

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849 views

Object with friction in circular motion caused by a string

A physics problem in my textbook reads: A 0.40kg ball, attached to the end of a horizontal cord, is rotated in a circle of radius 1.3m on a frictionless horizontal surface. If the cord will ...
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0answers
56 views

Modeling of exact stick-slip-friction using Linear complementarity problems (LCP)

Within my master's thesis, I try to model a machine elements and have to model the exact slipping and exact sticking between the bodies. So I noticed that such problems can be formulated as a LCP. ...
2
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0answers
45 views

Impact of friction on a fallen body [closed]

If a body travelling at speed falls to the ground through an arc from a certain height (someone walking who trips, for example), how does friction of the ground surface affect the forces impacting ...
8
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4answers
599 views

Is it correct that tires quickly get bald when used at high speed?

In my investigation, tires will quickly get bald if we ride a motorcycle at high speed. Is it correct? How to explain it in physics? Does the friction increase at high speed rotation? Update: The ...
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0answers
115 views

Particle sliding on a semisphere - solving the differential equations analytically [closed]

I have the following problem: A particle of mass $m$ is at rest at the top of a semispherical surface of radius $R$. After an impulse, it starts to slide along a meridian with speed $v_0$. The ...
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2answers
947 views

Is the newton's second law for a body experiencing a frictional force, relative to the surface in contact?

Let us consider a routine mechanics problem.A block of $ 10kg $ rests on another block of $ 2kg $ on a frictionless table.Let $ \mu = 0.2 $ be the coefficient of friction(let's neglect the difference ...
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0answers
51 views

Modeling Acoustic Lubrication

I thought about posting this question in the Biology StackExchange site but really it is just the application of my question that applies to biology not the core of the question itself. Can anyone ...
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4answers
2k views

Maximum acceleration for wheel-driven vehicle from standstill

Once I discussed cars and there was a question about rate at which the car gains its speed ($100\:\mathrm{km/h}$) from standstill (i.e. acceleration). At some point of conversation it came up that ...
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1answer
216 views

What would stop a pendulum swinging forever in vacuum? What kind of friction is in vacuum? [duplicate]

Suppose I put a pendulum of metal ball and very thin rope in highest achievable vacuum. What would keep it from not swinging forever?
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1answer
156 views

How much speed is maintained in a 90 degree turn? [closed]

How much speed is maintained in a 90 degree turn? Is there an equation for this? I was recently driving and took a 90 degree turn while coasting at 25 mph and it did not seem like I lost very much ...
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3answers
86 views

Is it possible to reach the edge of a room if there isn't any gravitational acceleration?

Consider that a large room(an indoor badminton court) is orbiting the earth with a person floating exactly at its center without any relative initial velocity. Consider that the person has no ...
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1answer
208 views

Why is this classical system seemingly non-deterministic?

So, I was solving this problem1 and I realized that the system given seems to be non-deterministic when analysed with classical laws. The situation is thus: A rope is wrapped for an angle of ...
1
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1answer
288 views

What is the friction between cylinder and wall (ground)?

A hollow cylinder (radius $R$) is rolling against the wall at angular speed $\omega$. The coefficient of friction between the cylinder and the wall(ground) is $\mu$. After how many rotations the ...
2
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2answers
441 views

Falling chain with friction

I really need some help with a physics problem, and I guess my doubt is more conceptual, than question based. But still, let me pose it to you: A uniform chain of mass $M$ and length $L$ lies on ...
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0answers
26 views

Static friction greater than kinetic friction [duplicate]

Please explain why static friction is greater than kinetic friction logically. Speak about it microscopically and tell what does happen on surfaces of objects by considering electromagnetic force ...
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2answers
3k views

How much force needed to push a car on neutral? [closed]

The car is a 2002 Toyota Corolla SE I have in my garage on a stone surface, I.e., the floor itself. What I want to know is how to determine the force needed to get it in motion at all. The curb ...
1
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1answer
570 views

How does rolling resistance of rail wheel depend on diameter?

Freight train is more efficient than truck due to lower rolling resistance. And I wonder which one has lower rolling resistance<>, small diameter or larger one or it doesn't not depend on diameter ...
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votes
1answer
92 views

Force-Weight Pinewood Derby Car [closed]

Force-Weight Pinewood Derby Car. I'm trying to make a fast derby car. I was wondering if I could make a car that can drop/eject weight once it comes off of the incline. Would that increase speed or ...
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4answers
3k views

Does ABS shorten stopping distance of a car?

ABS, from German Antiblockiersystem, is a device put in almost every new automobile. The web has lots of explanations about the system, how it works, but I don't understand how it shortens the way of ...
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4answers
1k views

Why do we take small steps while walking on ice?

When we walk on ice we should take small steps. Small steps ensure: a.)larger friction. b.)small friction. c.)larger normal force. d.)smaller normal force. The correct ...
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3answers
2k views

Would a pendulum swing indefinitely in a frictionless vacuum?

I am attempting to settle a friendly bet. Would a pendulum swing indefinitely in a hypothetical vacuum (i.e. no air resistance) having a hypothetical frictionless bearing (i.e. no energy lost due to ...
3
votes
2answers
558 views

A block on a wedge

The system is as follows - Friction exists only between the 2 blocks. I am trying to find out the accelerations of $m_1$ and $m_2$. Let $a_2$ be acceleration of $m_2$, and $a_x$ and $a_y$ be the ...
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1answer
78 views

A question about speed [closed]

A object with mass 0.5 kg slides in straight line for 200 m, where the friction act on it is 0.4 times the normal reaction acting on it. Find its initial speed. I let $u$ be the speed. ...
19
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4answers
2k views

Does a car consume more fuel when it's raining?

Yesterday my wife asked me that question, and I couldn't answer. Consider a car, in a sunny day, and that is consumes x gallons per mile. Considering that everything is equal, except that it's ...
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0answers
68 views

adhesion(bonding etc.) of materials and frictional force

I am studying material physics. I heard in the class that every adhesion or bonding can occur only with frictional force. Today, I tried to find a proper reference for this statement but I could ...
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1answer
299 views

Question on static friction [closed]

This is the question, and the answer is given as 2). Now my basic doubt is, are they asking us the direction of the total contact force on the object by the floor? Or, are they asking the direction ...
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1answer
424 views

Mechanics question (a block on top of a block) [closed]

This question is very similar to this one here. A block of mass $m_1$ is placed on another block of mass $m_2$ lying on a smooth horizontal surface. The coefficient of friction (static and ...
11
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2answers
465 views

The secret behind the spinning, asymmetrically weighted, 2D disk-shaped top?

When you spin an asymmetrically weighted, 2D disk-shaped top, the heavy part actually rises to the top. Why is this? http://www.youtube.com/watch?v=h0SZZTBQmEs ...
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2answers
130 views

What processes occur when a meteor enters the atmosphere?

What processes occur when a meteor enters earth's atmosphere and then what will be speed of meteor when it encounters air resistance?
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1answer
358 views

Understanding centripetal force vs frictional force diagrams?

I have an actual physics problem and also a conceptual question to go with it. From some test prep I was presented with this straight-forward question: What is the minimum radius that a cyclist can ...
0
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1answer
232 views

Friction acting on a particle on a rough place

If a particle on a rough inclined is attached to a spring so that the spring is parallel to the inclined place, when the particle is equilbrium just because of the weight of the particle extends the ...
4
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4answers
5k views

Static as opposed to Kinetic Friction in Rolling Motion

During analysis of rolling motion, why do we consider coefficient of friction as that of static friction and not kinetic friction?
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2answers
162 views

Is my physics correct or torque correct?

I would like to put this into a differential equation. This is what I have. $$r \times F = I \ddot\theta + \mu \dot\theta + k \theta$$ What I need verified: $\text{Torque} = I\ddot\theta + \mu ...
18
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2answers
791 views

How hot does the tip of a pencil get while writing?

When writing with a pencil, there seems to be quite a lot of friction - which seems like it would induce heat. How hot would the tip of a #2 pencil get writing on normal copy paper?
3
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2answers
250 views

Frictional Forces

In the figure, blocks A and B have weights of 45 N and 23 N, respectively. (a) Determine the minimum weight of block C to keep A from sliding if μs between A and the table is 0.21. (b) Block C ...
0
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1answer
410 views

Friction force and contact area [duplicate]

It's usually stated that the friction force is independent of the area of contact (Amontons' Second Law). I've always thought that this shouldn't be true, because the atraction between molecules ...
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2answers
1k views

Slowdown rate of rotating body due to friction force [closed]

This isn't a homework question, but it might as well be. The problem I have been pondering is: If a disc (or children's roundabout if you like), of radius r, mass m, is spun around it's center ...
6
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1answer
331 views

The quickest 6-3 play in baseball: to bounce or not to bounce?

What's the quickest way the get the ball (say from shortstop) into the first-baseman's glove, given some fixed initial (throwing) speed? Directly or with one bounce? I'm fairly sure that the answer ...
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1answer
270 views

Question on friction [closed]

Please look at the figure carefully. The question is written, and one has to match the two columns 1 and 2 given under "choices and explanation". Please tell me if I am really wrong, i.e. would you ...
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0answers
118 views

Is there any place you can safely skydive without a parachute?

While trying to explain to someone how a kitten walked away from a fall from a skyscraper I got to wondering if there's any place a human could do that and I find myself out of my depth. The only ...
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2answers
152 views

Does the slip-stick phenomenon have any application?

The slip-stick phenomenon is present all around us, be it the noise of car breaks or in earthquakes. But does it have any real-life application?
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1answer
507 views

Friction on a conveyor belt

I was surfing through an Olympiad paper and I was caught with this question. A block of mass 1 kg is stationary with respect to a conveyor belt that is accelerating with $1\, \tfrac{m}{s^2}$ ...
1
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1answer
3k views

Coefficients of friction for steel, aluminum & polymers

I am trying to analyse the problem of sticking an aluminum piece to a stainless steel piece only with pressure. The holding capacity of the system is determined by the static friction between the two ...
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3answers
190 views

Static friction force on a block in a tunnel

Linked to this question: Comparing Static Frictions Suppose there is a cuboidal vertical tunnel, and a cubical block in it such that all surface of the block are in contact with the four walls of the ...
5
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4answers
412 views

Comparing Static Frictions

In this figure, which of the static frictional forces will be more? My aim isn't to solve this particular problem but to learn how is static friction distributed . Since each of the rough-surfaces ...
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1answer
2k views

Work done by Static friction

Here $v1$ is relative to the block on which sphere is pure rolling but static friction isn't $0$ as of now . In the following diagram, is work done by static friction $0$ ?, since the point of ...
2
votes
2answers
1k views

Angular momentum conservation while internal frictional torque is present

So this appears in a problem which looks simple enough in its context; It's something like this: Two discs, A and B, are mounted coaxially on a vertical axle. The discs have moments of inertia $I$ ...
3
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1answer
740 views

Angular momentum after elastic collision

If two balls collide (elastically) and there is no friction between them, will their angular momentum change after the collision?
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1answer
95 views

Are there real life applications for Hausdorff dimensions, specifically crack formations?

I was curios about Hausdorff dimensions. They seem to neatly describe rough surfaces. So I was wondering if there are common applications of Hausdorff dimensions in things like complicated friction ...
20
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1answer
1k views

What determines the angle of the cushion on a pool table?

If you look at the cushions (bumpers) on a pool table, you'll see that they're not vertical. They're tilted inwards. About 10 years ago, I came across a physics exam in which one of the problems ...