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

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What is the force of friction between two bodies given their masses and a force pulling them as a unit accross a surface?

Where a force of 200N pulls two blocks together(as one system) across a horizontal table top(µ=0.800) $m_A$ = 5.00kg, $m_B$ = 10.0kg Find the acceleration of the system. Find f$_k$ between B and A ...
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1answer
408 views

How does the resistance force on a rolling ball depend on the ball radius?

A billiard ball set gently rolling on a billiard table slows and stops, because it is decelerated by resistance forces at the contact between the ball and table. I expect the magnitude of the ...
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2answers
164 views

Boy and box on ice

I have a troubles. Can you help me? I have a task, called "slippery activity". Boy (he has $m=45kg$) Stands at ice and tries to move a big box ($M=90kg$) with a string (rope). Boy's Slip ratio is ...
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2answers
2k views

How does rubbing cause the transfer of electrons from one object to the other? [duplicate]

I have just learnt about electrostatics. Why would there be a transfer of electrons? Is it because of the difference of the materials (i.e. triboelectric series)? So in the case of two different ...
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4answers
4k views

After what speed air friction starts to heat up an object?

I understand that air friction cools off an object at low speeds. For example, if you blow on a spoon of hot soup, it cools off. Or if you swing a hot frying pan in the air, it cools off faster. But ...
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1answer
180 views

Understanding Work and the conservation of energy

We have a car with a mass of $780 kg$ with travels with a speed of $50 km/h$. The car brakes and after $4,2m$ is stops completely. Warmth is created. Calculate the friction. I solved this easily, by ...
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3answers
988 views

Conservation of energy in objects at terminal velocities

In vacuum, object free falling under gravity, the sum of Gravitational Potential Energy(GPE) and Kinetic Energy (KE) is a constant. The GPE is a decreasing side of a quadratic and KE is a increasing ...
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1answer
186 views

Moving along friction surfaces

If a particle moves along a one dimensional surface with constant friction. As the particle moves from point $A$ to point $B$ it loses an amount of energy equals $E(A,B)$. Consider that the particle ...
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Why does a tire need to be filled with air?

The Mini 4WD's tires aren't full of air, and it can run. Also, the tank doesn't have tires with air. So, the question is: why do real cars on the road need to be filled with air? What is the idea ...
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0answers
45 views

Why do bigger tires = more friction? [duplicate]

Possible Duplicate: Why do people recommend wider tyres in car for better road grip? Static/kinetic friction says that the friction force is proportional to the normal force, via the ...
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0answers
140 views

Describing the movement of the object in a particular situation in Lagrangian way

Suppose there is a object M, (sliding motion) moving by the initial speed $v$ and the initial location $x_0$. Otherwise noted, friction is assumed to be nonexistent. It then meets a circular mold ...
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Is water considered a substance with low friction or high friction?

Like, for example, rubber is a substance with high friction, as an object with neither high or low friction would easily stop on it, and wouldn't skid. Ice is considered an object with low friction, ...
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2answers
277 views

Does air resistance ever slow a particle down to zero velocity?

If a particle moves in a place with air resistance (but no other forces), will it ever reach a zero velocity in finite time? The air resistance is proportional to some power of velocity - $v^\alpha$, ...
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1answer
107 views

Beer bottle leftovers pour quickly only after waiting?

Why is it that after pouring a delicious beer from a bottle, I can hold it upside down for several seconds without reward, but if I wait a bit, the remainder presumably settles at the bottom and ...
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0answers
21 views

Helpful tutorials on force [duplicate]

Possible Duplicate: List of good classical physics books I'm having a hard time understanding force in my highschool AP physics class, i looked through youtube but without luck. Could ...
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3answers
1k views

Is it possible to find out the distance traveled by a car if the force applied on it is given?

Say you have car which produces $F$ amount of force which is transferred to the wheels directly. Now assuming that there is air friction which is causing a retarding force proportional to the ...
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5answers
3k views

Physics behind Wheel Slipping

Lets say that I'm in a car and I apply full acceleration suddenly. Now, the wheels would slip and hence the car doesn't displace much. But If I start with some constant acceleration, slipping doesn't ...
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1answer
495 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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858 views

Why doesn't a fly fall off the wall?

Pretty simple question, but not an obvious answer at least not to me. I mean you can't just place a dead fly on the wall and expect it to stay there, he will fall off due to gravity. At first I ...
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2answers
943 views

Where does the lost energy go in a rubber band powering a rotating shaft?

Okay, I'm no physics whiz, and this has me stumped. You know those toy airplanes you can get with the rubber-band driven propellers? You twist the propeller a bunch of times, and this stores ...
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1answer
185 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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2answers
359 views

Kinematics - Find theta with Coefficient of Friction?

I recently found a problem that looked like this: A box sits on a horizontal wooden ramp. The coefficient of static friction between the box and the ramp is ...
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2answers
496 views

Force applied perpendicular to direction of motion, static or kinetic friction?

Let's assume we have a 1 kg cube on a flat uniform surface. The coefficients of friction between them are $\mu_k = 0.25$ and $\mu_s = 0.50$. This cube is moving at 1 m/s in the y direction, with ...
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1answer
927 views

Direction of friction on particle placed on a rotating turntable

If a particle is placed on a rotating turntable then the particle has a tendency to slip tangentially with respect to the underneath surface... So the friction should act tangentially to the ...
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1answer
205 views

Friction in Physics

I've heard a lot of things about Friction like friction between solids, liquids and gases. Even practical applications like motion of objects (Like car moving on road), etc. involve friction. But, do ...
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Physics behind Water drops during falling from a tap

what is physics behind Water drops during falling from a tap. water drop animation A drop or droplet is a small column of liquid, bounded completely or almost completely by free surfaces. Why Water ...
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1answer
3k views

How to calculate work done by variable kinetic friction force?

A heavy chain with a mass per unit length $\rho$ is pulled by the constant force $F$ along a horizontal surface consisting of a smooth section and a rough section. The chain is initially at rest on ...
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1answer
447 views

Change in appearance of liquid drop due to gravity

A liquid drop is spherical in shape due to surface tension. But why does it appear as a vertical line under the free-fall due to gravity? (E.g. During a rain - falling raindrop) Is there a specified ...
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3answers
1k views

How do I find work done by friction over a curve represented by a polynomial?

I am facing a problem in Physics. Problem: What will be the work done by the frictional force over a polynomial curve if a body is sliding on this polynomial($a+bx+cx^2+dx^3+\ldots$) curve from rest ...
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1answer
257 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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2answers
158 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
366 views

Is my understanding of the mechanics of skidding correct?

I'm trying to understand the mechanics which determine if a car making a turn will skid. Are the following correct or incorrect: A vehicle making a turn will skid unless the centripetal force is ...
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4answers
285 views

Friction at zero temperature?

By the fluctuation-dissipation theorem (detailed-balance for Langevin equation), $$\sigma^2 = 2 \gamma k_B T$$ where $\sigma$ is the variance of noise, $\gamma$ is a friction coefficient, $k_B$ is ...
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1answer
480 views

When does centripetal force cause constant circular motion?

As far as I know, if an object has a speed $s$ and a force is applied to it which generates an acceleration of $s^2/r$, then the object will start moving in a circle of radius $r$. Also, as far as I ...
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1answer
148 views

What prevents a natural fibers rope from untwisting when it is elongated?

I don't understand why a rope doesn't untwist when an attempt is made to increase its length. It seems counter-intuitive to me, because untwisting would allow the rope to increase its length, but in ...
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2answers
1k views

What would it feel like to touch a frictionless surface

Assume there is a completely frictionless surface. Would touching such a surface be possible? If so, what would it feel to the touch?
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Why do people recommend wider tyres in car for better road grip?

Tyre companies boast of their wider tires for better grip on road. Also, the F1 cars have broad tires for better grip. But as far as I know Friction does not depend on the surface area of contact ...
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3answers
2k views

Does friction decrease as objects move faster against each other?

I was told that the faster two objects move against each other, the less the friction between them would be… compared to if they were moving slower. In physics class, we always use the coefficient of ...
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1answer
460 views

What forces act on a person sitting in a chair with wheels when they push off another stationary object

What is slowing me down when I push off my desk? What are the "Major" contributors? and Does how hard I push with one hand (or with two hands) make a significant difference?
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1answer
281 views

What is the function of the top point of a bouncing ball?

A ball is thrown away as parallel to x axis from M(0,h) point with speed V . After each jumping on x axis , it can reach half of previous height as shown in the figure.(Assume that no any air ...
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1answer
159 views

Is energy “destroyed” when walking?

Conservation of energy states energy can't be destroyed, but isn't energy used up when walking in a straight line? If your not walking up a slope, kinetic energy isn't converted to gravitational ...
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1answer
501 views

How calculate the angle to launch an object at the maximum distance?

Suppose that you want to launch an object that travels the longest distance, given the starting speed (or the force applied). You have to determine the angle that al you to reach the longest distance, ...
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1answer
188 views

Does friction act in the same way in different directions?

A physics textbook is launched up a rough incline with a kinetic energy of $X$ joules. When the book comes momentarily to rest near the top of the incline, it has only gained ($X-20$) joules of ...
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3answers
780 views

Finding Distance an Object Travels Up an Incline After Launch

I've been doing a review for an introductory physics course final. I have a question on one problem though. Here is the problem: A mass (M=2kg) is placed in front of a spring with k=900N/m, ...
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2answers
1k views

Conservation of angular momentum in helicopter

I have a small RC-controlled toy helicopter with removable tail rotor. Suppose I remove the tail rotor, hold the tail with my hand, start the rotor until it moves with constant angular velocity and ...
3
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5answers
1k views

Why would it be true that people with longer legs walk faster than ones with shorter legs?

When a person walks, the only force acting on him is the force of friction between him and the ground (neglecting air resistance and all). The magnitude of acceleration due to this force is ...
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5answers
9k views

What does it mean for two objects to “touch”?

If you've ever been annoyingly poked by a geek, you might be familiar with the semi-nerdy obnoxious response of "I'm not actually touching you! The electrons in the atoms of my skin are just ...
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1answer
406 views

Does Polytetrafluoroethylene (Teflon) have low wind resistance?

It is reasonable to assume that covering for example an airplane with Teflon would lead to it having lower wind resistance? The reason why I ask is that Teflon "has one of the lowest coefficients of ...
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1answer
346 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
106 views

Is this a correct addition to a pipe friction loss calculation?

I've been using this online calculator to work out the difference in pressure and flow between two ends of a pipe: Pipe Friction Calculation for Fluid Flow in a Pipe So far most of it makes sense, ...