Coefficient of friction Definition and 411 Threads

Homework Statement The coefficient of static and kinetic friction is constant for a specific surface. On an incline plane s and k are both equal to tan of the inclined angle. If the angle increases then tan changes which means the coefficient of friction changes. How is this so? Homework...

Hello all I'm trying to calculate a torque needed to tighten a threaded terminal. (Both male and female parts are copper alloy) I'm using Motosh's equation which requires me to use the coefficient of friction. Web sources tells me that the copper-copper coefficient of friction is 1.0. The...

Homework Statement Hi, I was wondering how you would isolate for and calculate the coefficient of friction in an Atwood pulley, with one fixed pulley, with two masses hanging off of it on either side. There is no table or surface that the masses are touching or resting on, they are both...

I understand that most likely there are no accident experts on this forum and I am not looking for one per-say. I was in an accident where I turned left after entering the intersection on a yellow, pausing for a red and then proceeding, only to be hit by a guy running the red light. We both...

Homework Statement A box of textbooks at unknown mass rests on a loading ramp that makes an angle α = 16o with the horizontal. The coefficient of static friction is 0.30, and kinetic friction is 0.25. Then the box is released. (a) Will it start sliding down the ramp? (a) Find the normal force...

Hello physics forums, I recently carried out an experiment testing the coefficient of friction of different grit sandpaper My data supports that when you raise grit you decrease the cof. My problem is WHY, why does the size of the grit have any impact on the coefficient of friction. Any ideas...

Homework Statement A 70-kg skier is in a tuck position and moving down a 20-degree hill. Air resistance applies a resultant force of 15 N against the movement of the skier. The coefficient of friction between the skis and the snow is 0.09. What is the resultant downhill force acting on the...

Homework Statement So far i know that the uncertainty of the force of friction is +/- 0.1 and the uncertainty of the force normal is +/- 0.1 also. Homework Equations Force of friction=(myoo)(force normal) Myoo= force friction / force normal The Attempt at a Solution My data is Force of...

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Homework Statement I'm having trouble finding the coefficient of kinetic friction for a lab using spring scales. Mass=.411kg Normal Force=4.0278 Average Pull Force=.46N Frictional Force= -.46NHomework Equations μ k = Fk / N. The Attempt at a Solution μ k = -.46N/4.0278 μ k = -.1142

Homework Statement A small block sits at the midpoint of a 2.0 m plank lying on a level floor. A student slowly raises one end of the plank until the block starts to slide. At that instant, the raised end is 0.55 m above the floor. Find the coefficient of static friction between block and...

Homework Statement A child pulls a friend on a sled. The child maintains a constant tension of 29.4 N in the rope. The combined mass of the friend and sled is 30.0 kg, and the coefficient of sliding friction between the sled and snow is 0.1. How far can the child pull her friend in 6 sec...

Homework Statement When an 8.0 N force is exerted horizontally on a 10.0 kg block, the block’s acceleration across a level surface is 0.2 m/s2. a. Find the coefficient of kinetic friction between the block and the surface. b. Find the frictional force on the block. c. Find the net...

I am having my students do a lab to calculate the coefficient of static friction along a ramp. They are calculating the coefficient of static friction between felt and the table to be something like 0.40, yet when i did this lab, but along a horizontal surface, and not with a ramp, i get a...

Homework Statement why the µ for block is 0.3(between B and A) ? why can't be µ= 0.4( between B and C) ?? Homework EquationsThe Attempt at a Solution

Homework Statement A 1000N crate is being pushes across a level floor at a constant speed by a force (F) of 300N at an angle of 20 degrees below the horizontal, what is the coefficient of kinetic force? Homework Equations Fk= uk*N uk= Fk/N[/B] Fk=F2 The Attempt at a Solution in the back of...

Homework Statement A lab I've performed was measured using forces. As the mass increases, the force does as well. The inclined plane is at an angle of 30 degrees. Now, finding the coefficient, should the kinetic and static friction be decreasing on a plane? I've measured the frictions on a flat...

Homework Statement 1. A pulley 150 mm diameter is driven directly by an electric motor at 250 revs min–1. A V-belt is used to transmit power from this pulley to a second pulley 400 mm diameter against a load of 200 Nm. The distance between the centre of the pulleys is 600 mm, the included...

Homework Statement The top of a ladder of L and mass m is connected to a wall by a horizontal cable. The ladder makes an angle Θ=60 with the horizontal. A woman of mass 2m finds that as she climbs the ladder, the ladder begins to slip when she is one-third of the way up the ladder. Find the...

I'm trying to get my head around the calculation for coefficient of friction: COF = Friction/Normal force. And what happens if you vary normal force. Am I right in saying: The COF is a constant - every pair of materials has a specific COF which is independent of how hard they are pressed...

Homework Statement I had a question on my test that went something like: "A 20kg box is being pulled at an angle of 37 degrees across the floor with a force of 300N at a constant velocity. What is the coefficient of friction?" Homework Equations The equations I used to solve it were: Fpx= Fp...

Homework Statement A girl, with the mass m, slides down an icy slope at the time t1=τ. The slope is inclined at 30° below horizontal. The coefficient of kinetic friction between the girl and icy slope is μk. The girl notices that she can slide down the slope significantly faster if she sits on...

Homework Statement The figure shows an adjustable pipe wrench, drawn to scale. The geometry of the mechanism is arranged so that the jaws clamp more tightly as force is applied to the handle. Friction between the jaws and the pipe transfers a torque from the jaws to the pipe. Find the critical...

Homework Statement Calculate the force of friction on a toy car as it rolls across a flat floor. Given: mass = 0.293kg time = 3.66 s displacement = 8.7Homework Equations Fnet = mass x acceleration displacement = [(velocity1 + velocity2)/2] time velocity2 = velocity1 + acceleration(time)The...

I need to measure the co-efficient of friction of rubber (elastomer) seal on steel. How can I do this by experimentally ? I appreciate your any kinds of help regarding this issue. Thanks in advance.

Just wondering, what would be the lowest coefficient of friction value we know nowadays? From what material is it? Does the temperature between two surfaces interferes on the friction coefficient value?

Homework Statement Hey. I was doing some exam practice questions, but I hit a snag with this one and can't quite work out how to proceed. A 6kg block at rest is pulled along a horizontal surface by force F→ at angle θ. Given that the coefficient of kinetic friction is 0.15, find the optimal...

Homework Statement Coefficient of friction of a flat belt and of a vee belt Homework Equations I know the lap angle, m2, T2, T1/T2 and ln (T1/T2) for the flat belt and lap angle, m2, T2, T1/T2 and ln (T1/T2) The Attempt at a Solution I attempted to find it by plotting a graph using the lap...

Homework Statement A team of six poodles are pulling a 14.0 kg sled at 8.0 m/s IF the dogs are applying a 66N force, find the coefficient of kinetic friction Homework Equations Ff=u*Fn Fnet=ma Fnet=(-Ff)+FaThe Attempt at a Solution I honestly have no clue where to start for this question.

Can anyone explain why, if you increase the CoF of the belt on a V-Belt pulley system, you'd get less torque? I've increased my CoF in the V-Belt tension formula. You'd have thought that the torque would increase with a belt with a greater CoF?

Homework Statement A hollow spherical shell with mass 2.50kg rolls without slipping down a slope that makes an angle of 33.0 with the horizontal. Find the minimum coefficient of friction μ needed to prevent the spherical shell from slipping as it rolls down the slope. Homework EquationsThe...

Homework Statement A box has the mas 50.0Kg. The box slides on a horizontal surface that has friction. The box has the velocity 3.00m/s when its 0.600m away from a spring with negligible mass and the force coefficent 20Kn/m. The box hits the spring and comes to a momentary rest after...

I said stay the same, the definition of co efficient is here http://simple.wikipedia.org/wiki/Coefficient_of_friction but the main part i saw not only here was "The coefficient of friction is dimensionless, meaning it does not have any units. It is a...

[Moderator note: Moved from General Physics so no template.] An object slides down an inclined plane where there is friction. The time it takes the objects to slide down the plane is 5/4 times longer than the time it takes the same objects to slide down the plane without friction. Calculate the...

Homework Statement The rectangle in the drawing is held by the horizontal rope and the friction on the wall. What's the minimal coefficient of friction Homework Equations Friction force: f=μN The Attempt at a Solution Moments round the point of contact with the wall. the side of the rectangle...

Homework Statement 3 cylinders of mass m and radius 0.5[m]. what is the minimum coefficient of friction between them. Homework Equations Friction: f=μN The Attempt at a Solution f, the friction force, balances the torque of the weight: $$mg\cos30^0\cdot0.5\sin30^0=\mu\cdot mg\cos30^0\cdot...

Homework Statement A rod of mass M and length L is placed horizontally on a table such that the center of mass is a distance L/6 from the edge of the table (CoM is hanging off the table). The rod is released from rest and slips after reaching an angle θ. Find the coefficient of friction \mu 2...

So I have a physics midterm tomorrow that will have a five part, 10 point question about the following "an object pushed across a horizontal surface. You should be able to calculate net force, frictional forces from the coefficient of friction, acceleration, velocity, momentum, impulse, and...

Homework Statement I have no values at all, so it's just going to be the variables in the relevant equations. I need to define mu using those variables. A carousel is moving in a circle at velocity v and has a radius r. It is moving fast enough that each person with mass m is pinned against the...

I have tried this question but I seem not to be getting any where. Qn; An ice-hockey puck is struck from one end of a rink of length 27 m towards the other end. The initial speed is 6m/s, and the puck rebounds from the boundary fence at the other end with a speed which is 0.75 times the speed...

I'm teaching myself Physics (I really want to study Physics in college), and this is one of the few places where I can ask for help. I hope my questions aren't so silly. 1. Homework Statement (a) If half of the weight of a small ##1.00×10^3kg## utility truck is supported by its two drive...

Homework Statement We're told to find the coefficient of friction for a mousetrap car that we've made, using values that we attained ourselves. We released the arm of the mousetrap onto a scale to find Fa → 1.0*10^2 Newtons. This is how we found Fa: [FONT=Courier New]m = 1.020kg (←mousetrap...

Homework Statement The surfaces of two blocks are roughened so that they do not slide against each other when a force of 30N is applied to the bottom block. 1.Find the force of friction between the two blocks. 2. Find the minimum coefficient of friction needed between the two blocks so that...

i've been searching for the friction coefficient between medium carbon steels but can't find it, and also i see everywhere the yield stress of materials but i can't find the compressive stress of materials

I have a problem need to be solved here. Someone told me that the friction force must always have the friction coefficient. Is it right or wrong? and we can not calculate the friction force without friction coefficient because this force is only calculated by the coefficient and the Normal...

Homework Statement You are pushing a 53 kg crate at a constant velocity up a ramp onto a truck. The ramp makes an angle of 22 degrees with the horizontal. If your applied force is 373 N, what is the coefficient of friction between the crate and the ramp? Homework Equations μ =...

Need to know about coefficient of friction for my exam. http://easycalculation.com/physics/classical-physics/friction-table.php This site shows coefficient of friction of various materials to materials. But no calculations are given. Can somebody help me on how to calculate the...

My textbook says that the value of the coefficient of friction lies between 0.1 and 1.5. But I see no reason why it can't be 2,3,4,5 etc. One just needs to apply a force greater enough to move an object if the coefficient of friction has a greater value. What is the actual thing about it?

How Co-efficient of static friction depends upon temperature? What happens to the material when increase/decrease the temp. of a material ?

Homework Statement a square box held with a person's fingers pushing downward one quarter of the way along the top of the box and with their thumb pushing side wards on the bottom of the side face of the box. Friction between the person's fingers and the box is obviously very important if...