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

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Calculating the frictional force

Here's my problem and the work I've done. The time is already past for me to submit the answer, but I want to know where I went wrong and why I was wrong. The 2-kg box slides down a vertical wall ...
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1answer
222 views

Circular motion question

(Q) Find the maximum speed at which a truck can safely travel without toppling over, on a curve of radius 250m. The height of the centre of gravity of the truck above the ground is 1.5m and the ...
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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 ...
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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 ...
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505 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 $1\, \tfrac{m}{s^2}$ ...
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254 views

calculating work done by friction

I want to calculate the work done by friction if the length $L$ of uniform rope on the table slides off. There is friction between the cord and the table with coefficient of kinetic friction $\mu_k$. ...
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353 views

How would you use the Euler-Lagrange equation to predict the motion of projectiles with linear (Stokes) drag (but no wind)?

My first instinct would be to use the force $$\vec{F} =- \alpha \vec{v}$$ and therefore $$V(\vec{r}) = \alpha \int_C \vec{v}\cdot d\vec{s} = \alpha \int_C \vec{v}\cdot \vec{v} dt = \alpha \int_C ...
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686 views

Ropes and Pulleys - Really unintuitive answer

I usually don't want to do this, but please go to this link, the solution is too big to post it here http://engineering.union.edu/~curreyj/MER-201_files/Exam2_2_26_09_Solution.pdf And go to page 5 ...
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1answer
2k views

Two problems with free body diagrams. Contradictions (solutions are provided)

This problem is similar, but also different question from my previous question. They are both unfortunately long. Problem/Solution #1 ! ! Quick Concept Check a) Could someone briefly explain to me ...
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435 views

Linear motion with and without Friction

Could we still use Newtonian mechanics in a frictionless world?
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1answer
33 views

Accelerated wedge [closed]

Consider the following figure, where a mass $m$ is placed on a wedge which is accelerated to the right ($\vec a$) which could be negative. The coefficient of friction between the mass and the wedge ...
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1answer
87 views

Static and kinetic friction [closed]

Say you have block1 on top of block 2 and the whole system is accelerating toward the right at a certain acceleration. Due to inertia block 1 wants to move backward to the left so there has to be a ...
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1answer
58 views

Calculate coefficient of friction from deceleration with and without conservation of energy

How can I solve the following problem? A block that moves at the speed of 120 cm / s keep going for 70 cm before stopping. What's the coefficient of friction between block and table calculated ...
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31 views

Pseudoforce and friction: confusion

Consider the following situation. A block of mass $M$ is resting on a rough horizontal ground, and a frame is moving towards the right horizontally with an acceleration $a$. Suppose the coefficient of ...
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1answer
48 views

Modeling a stool with three legs pushed on one leg

If a stool with three legs is pushed (horizontally) on one leg in the direction of the axis passing through the other two legs, it starts both moving and rotating. Is it correct to assume 1/3 of ...
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1answer
143 views

Moving wedge and pulley system

A wedge of mass $M$ rests on a rough horizontal surface with coefficient of static friction $\mu$. The face of the wedge is a smooth plane inclined at an angle $ \alpha$ to the horizontal. A mass ...
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2answers
94 views

Does distance traveled by a vehicle after its engine has been switched off depend on its mass at all?

A vehicle moving with some velocity on a rough horizontal road finally comes to rest after its engine has been turned off. Intuitively, it seems a vehicle with greater mass would stop first because it ...
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3answers
125 views

Why doesn't a block rotate due to friction?

In a horizontal surface, a block (cube) is sliding due to a sudden push. When the block slides, there is frictional force which is acting on the block. Frictional force will have a torque around ...
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321 views

Water Pressure Calculation for a volume of water at a given height

I'm looking to create a rain harvesting system. I have a 275 gallon IBC tote that is 48" x 40" x 46". I have an adapter for a 3/4 garden hose at the bottom of the IBC tote. I'm trying to figure out ...
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2answers
125 views

Why neglect friction when computing torque?

There is a block of wood on a plank, with friction, and the block is moving down with uniform speed. They are asking what is the torque acting through the center of the block. My doubt is that ...
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2answers
71 views

Friction fire lighting

Having watched a few youtube guides on making a fire by friction, namely the spindle and fireboard method, I've heard many of the instructors talk about how the shape of the spindle at its ends should ...
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1answer
114 views

Calculating the time to stop a wheel with friction [closed]

I'm trying to solve the following problem, but i have no idea how to begin. A wheel of mass $M$, radius of gyration $k$, spins smoothly on a fixed horizontal axle of radius a which passes through ...
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1answer
67 views

Can a magnetic field hold a state of supercavitation if a magnetic field could be placed inside of the bubble of the supercavitation?

I have a question that I am just curious about. Two principles: Magnetic fields and Magnetic susceptibility Supercavitation is the use of cavitation effects to create a bubble of gas inside a ...
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1answer
83 views

Shaking water inside bowl causes waves but why does the water stabilize?

Suppose you shake water inside a container, then at first the waves goes up and down strongly but they gradually dissipate. What makes them dissipate?
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3k views

Does the contact area affect friction forces?

I recall studying a law of friction some years ago, in engineering school. All I remember is that when first approximation was taken, the popular $f=k \times N$ was derived. What could that be? Or if ...
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1answer
420 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 ...
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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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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 ...
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1answer
55 views

What is $\gamma$ in the damping equation?

$x''+\gamma x'+w_0^2x=0$ That is the general equation for damped harmonic motion. What is the term or name that describes $\gamma$? Is it called the damping constant? I know its the ration between ...
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1answer
2k views

Work done by friction

Suppose we have a block of mass $M$ and we are moving it up a curve, very slowly ($a=0$). The surface is not smooth, and coefficient of friction is $\mu=\mu_s=\mu_k$. To move the block we apply a ...
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2answers
611 views

Why is simple harmonic motion called so?

Is the motion of a simple pendulum, a simple harmonic motion? It stops vibrating after sometime.
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1answer
65 views

friction on atomic scale

I am getting into friction on an atomic scale. For instance, take two rigid layers of atoms of the kind A that are placed on top of each other, just like putting two boards of wood on top of each ...
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3answers
2k views

Preventing a block from sliding on a plane (with friction)

Assume a small square block $m$ is sitting on a larger wedge-shaped block of mass $M$ at an upper angle $\theta$ such that the little block will slide on the big block if both are started from rest ...
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1answer
600 views

Overcoming Friction

Let's say a box is moved by attaching a rope to it and pulling with an applied force at a certain angle. Now, let's say that this is being done on an inclined ramp. How would I find the acceleration? ...
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213 views

Friction between atoms in spring

if i doing experiment on spring-mass system in vaccum,if i pull the to some extent (within elastic limit of spring) & let it go,will the system oscillate indefinitely? (neglect contact frictions ...
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285 views

What controls whether a ball will skid or roll?

A billard ball is struck with a cue. The line of action of the applied impulse is horizontal and passes through the center of the ball. The initial velocity $v_0$ of the ball, its radius $R$, its mass ...
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177 views

What is the origin of nonconservative force?

My understanding about conservative force is a force that its work is independent of path such that we can construct another form of the work called potential to make our life easier. For friction, ...
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1answer
391 views

How to model water flow with and without friction against other objects?

I am interested in modeling water flow including boundary flow (with friction) against other objects in the path of the water flow. I'm not a physicist but I am interested to learn the relevant ...
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1answer
353 views

What conditions must be met for a ball to roll perfectly down an incline without slipping?

What conditions must be met for a ball to roll perfectly down an incline without slipping? A mathematically rigorous definition, please. I honestly don't know where to begin with answering this ...
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2answers
164 views

If a puck on ice deccelarates, is its speed “v = v0 - t * a” or is it “v = v0 -k * v0”?

I've been wondering about a puck sliding on ice or a puck in an air hockey table game. If a puck is hit and we start watching it as soon as it has reached its maximum speed and starts becoming slower, ...
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1answer
20 views

How to calculate heat generated from cosmic dust in space? [duplicate]

Say I have a spaceship, and I'm flying it through space at a constant high velocity V. The spaceship is pretty large (big surface area). In space however, there is cosmic dust scattered throughout ...
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36 views

Finding equation for acceleration using mass1, mass2, gravity, theta, and Mu [closed]

So, the only question I could not solve in this chapter for AP Physics, and I really want to understand it. We have a situation like this: There is a box sitting on an incline. We are trying to ...
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0answers
46 views

How torque and friction cause wheel to roll

I apologize if this question has been answered before, but I did not find the explanation that I needed. If a torque is applied to a wheel situated on a frictional surface, what forces cause the ...
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0answers
265 views

Tension Problem: Solve for T for two sliding blocks connected by a string [closed]

The problem: Two blocks made of different materials connected together by a thin cord, slide down a plane ramp inclined at an angle θ to the horizontal as shown in the figure (block B is above ...
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0answers
21 views

Why do skidding wheels have less traction than non skidding wheels? [duplicate]

I do not understand in terms of coefficients of friction why this happens? From my understanding the ground and the tire still have the same coefficients of friction right? So why is there less ...
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39 views

Inclined plane problem with friction [closed]

A block of mass 6.0 kg slides from rest at a height of 2.0 m down to a horizontal surface where it passes over a 1.5 m rough patch. After crossing this patch it climbs up another incline which is at ...
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24 views

Static Friction on a Circular Road [duplicate]

I was recently brushing up on my dynamics, when I saw the interpretation of how a car moves in a circular road. Apparently, the car can stay in a circle due to static friction acting inwards. But I ...
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45 views

How do whitening toothbrushes work?

Certain "whitening" toothbrushes are sold and I was wondering about the mechanisms behind the tooth whitening process. I suspect this is related to the shape and arrangement of the fibres, probably ...
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32 views

Friction effects on ball motion direction when crossing surfaces edges

For a ball rolling from a high friction coefficient surface to an adjacent low friction coefficient surface. When the ball crosses the boundary at an angle, I believe it changes angle of velocity, ...
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1answer
50 views

Throwing ball against oily/slippery wall

I would like to know whether a ball bounces back normally if you throw it against an oily wall. Like a wall watered down with oil. Basically I want to know if it will actually slip before bouncing ...