Friction Definition and 998 Threads

Homework Statement A rotating flywheel slows down only because of friction in its bearings. At the initial time ti, the angular speed of the flywheel is 2.0 rad/s. The power due to friction at a later time tf is half of the power due to friction at time ti. The angular displacement of the...

Homework Statement A 1.0x10^3 kg elevator carries a maximum load of 800kg Velocity = 3m/s Distance = .01km Net work = 13640J Homework Equations Force of friction = (m)(mu)(gravity) The Attempt at a Solution Gravity = friction 9.8 = (mu)(17640) .001 = mu

Homework Statement A boat of mass 1000 kg is moving at 25 m/s. The friction force ##f## is proportional to the speed ##v## of the boat, ##f = 70v##. How many time will take for the boat to reduce its speed to 12.5 m/s? Homework Equations ##\vec{F_r} = m \vec{a_r}## The Attempt at a Solution...

Homework Statement I have a Force Normal vs Force Friction Graph and I wan to find the coefficient of friction from the graph. Homework Equations The Attempt at a Solution I have tried the formula ff= uFN but my teacher is looking for me to do it using the graph

In my experiments, on a flat plane, when I incrementally increase the normal force acting on a rubber block, I am measuring a decrease in the static coefficient of friction. I am also measuring the friction force, which increases as normal force increases BUT this is not a proportional increase...

Let's say you two objects with weight of 2 kilograms but one is narrower and one wider. They are said to be similar coefficient of friction against a surface.. but what if the surface is rough? Won't the wider object has more friction? Or still the same? If still the same.. what if the...

Homework Statement A child is playing with their Hot Wheel cars. They have set up a track which is initially horizontal but then ascends to a second horizontal section which is 50 cm higher than the initial track. The track is friction-less until the car reaches the upper section of the track...

I am aware that there needs to be two materials for there to be a coefficient of friction, but I mean in general. For example, I know synthetic setae are very resistant to slipping on surfaces.

This issue was the subject of this old post, now closed. The question is: can a coefficient of friction (static) be larger than one? I see confusing replies. Someone talks about glue, but I'm not convinced about that. It's a bit like wondering about the coefficient of friction of a wooden plank...

(mentor note: moved here from a non-homework thread) Hello I am trying to find the time it will take for a parcel to pass over one conveyor belt The conveyor on the right is Conveyor A The conveyor on the left is Conveyor B they both have a length of 700mm Conveyor A has a constant speed of...

Homework Statement Vo = 5m/s W to the left = 6N Ffriction = 2N F to the left = W - Friction = 4 N m = 1kg g = 10 m/s^2 Ramp length = 10m sin a = 3/5 cos a = 4/5 Homework Equations F = ma Vt ^2 = Vo^2 + 2as Vt = Vo + at The Attempt at a Solution Outside force (1) to cancel acceleration from...

Hi Guy's, I'm starting a project to explore the physics of hysteresis friction between two surfaces. One flat metal surface is considered to have zero compressibility but does have grooves interrupting the sliding action. The second material (organic elastomeric compound) also having a flat...

Homework Statement The 1.0 kg block in the figure is tied to the wall with a rope. It sits on top of the 2.0 kg block. The lower block is pulled to the right with a tension force of 20 N. The coefficient of kinetic friction at both the lower and upper surfaces of the 2.0 kg block is μk = 0.300...

Homework Statement I am investigating a scenario where a pendulum with a bob attached is released from an angle and pushes a box to a certain distance. My goal is to find the coefficient of friction between the box and the surface it moved on. I have measurements for: - mass of the bob (125...

Homework Statement A sledge of mass m1 is pulled horizontally with a force F. On the sledge there is a body of mass m2 that can slide on the horizontal platform of the sledge with the friction coefficient μ. Another sledge of mass m3 is tied with a horizontal string of the body m2. Between the...

Greeting fellow physicists, I have been having some questions from my AP Physics C: Mechanics students about the direction of friction in rolling. Here are a few situations. 1. For a wheel that is accelerating to the right while rolling smoothly, it must also be rotating clockwise. In order to...

From Painleve we know that Coulomb's law of friction being applied to rigid bodies systems may produce contradictions. Painleve constructed several examples of such contradictions, so called Painleve's paradoxes, see [Painleve P. Leçons sur le frottement. P.: Hermann, 1895]. Those examples...

Homework Statement Ok so there was a question on a physics quiz I did that I have no idea how to answer. There was a roller coaster going down a hill with an initial velocity of 1.67m/s. The hill is 60m long and had an angle of 40 degrees. There is a coefficient of friction of 0.100 with the...

Homework Statement Block A, with weight 3w, slides down an inclined plane S of slope angle 36.9 degrees at a constant speed while plank B, with weight w, rests on top of A and is attached by a cord to the wall. If the coefficient of kinetic friction is the same between A and B and between S...

If I push an object such as a cylinder of wood along a flat table (flat face of cylinder in contact with the table) through it's center of mass, the friction or energy required is not dependent of the surface area the block makes with the table, Friction = μ N, correct? And the energy required =...

Question: If a 1000kg Mass resting on a friction free airbed is accelerated from zero to 1 Metre per second by a drive motor, then the motor is disconnected, how much electrical braking energy could be recovered from the moving mass in percentage terms using modern technology. Thank you in...

Hi there, I was thinking that static friction works in opposition to a reaction force like the force of a fridge against you as you push it. However, since you are pushing horizontally and friction works against you why is it equal or greater than the reaction force? Will the force get...

Hello, I have been learning about energy and work in my 100 level physics class and I got to thinking: W = F*d But I'm wondering how this works in the case of static friction. For instance, if I take a really heavy object and apply a force to it that isn't enough to move it, the distance it...

Is there any case example where the friction force DOESNOT oppose the motion, but rather PROVOKES the motion of some object? I wondered about this all day long :D

Homework Statement [/B] In an automatic materials handeling operation, metal blocks of 1.5 kg each are pushed one at a time from bottom of a stack six blocks high. If the coefficient of friction is 0.25, determine the horizontal force required to push. There is a figure bellow. I try to...

In a classic problem where a man walks along the length of a boat floating on the surface of water without friction, Should the net work done due to static friction between the man and the boat be zero. If the length of the boat is L, its mass being M, and the mass of the man being m, the...

Question: A large box of mass M is pulled across a horizontal, friction-less surface by a horizontal rope with tension T. A small box mass m sits on top of the box. The coefficients of static and kinetic frciton between the two boxes are Us and Uk. find an expreeion for the maximum tension Tmax...

Homework Statement An disk has a radius of 0.2 meters. A lump of putty with a coefficient of static friction of 0.9 is stuck on the edge of the disk. Let's say the disk starts at rest and gradually speeds up. At what speed will the putty just barely be able to stay in place on the edge of the...

Hello! I am an AP Physics student and had a quick question for validity. I was prompted with this question in class today: Example 7: An 8-meter ladder of weight 355 N leans at an angle of 50° to the floor against a smooth vertical wall. Assume the center of weight (gravity) for the ladder is at...

Homework Statement Consider a uniform solid disk of mass m and radius R, rolling without slipping down an inclined plane with an angle γ to the horizontal. The instantaneous point of contact between the disk and the incline is called P. Homework Equations ma = mgsinγ - μmgcosγ Γ = Rmgsinγ-Rμmg...

Hi everyone, I'm having a difficult time figuring out this problem. Could someone give me some pointers? I set up the equations and the free body diagrams (hopefully they're correct) ; all I have to do now is solve for F.1. Homework Statement A block of mass m is on top of a block of mass M =...

I thought this would be the most logical way to post this, but give me some grace if it is not because this is my first time posting on this site (then relinquish the grace and tell me how to do it properly haha). First: When a physics problem says "sliding past point P" does that mean it stops...

Homework Statement A tractor moves, at constant velocity, on a flat surface with known friction coefficient μ (0.24), ten objects each of which has known mass m (12 kg). It does so for a known distance d (500 m), and it takes known time t (150s) to do so. Calculate the Power of the tractor...

Homework Statement This is the problem http://imgur.com/a/1XFlt 2. Homework Equations This is the given FBD http://imgur.com/a/CURqA 3. The Attempt at a Solution Now the car should have a tendency to slip down the ramp thus causing the frictional force to oppose this motion. But the...

Hi all, I have problem to solve this question: Wb=150N Wa=50N T=150N alph =? µ =? - There is friction between A and B only(Between A and the ramp there isn't). - A and B not moving(first Newton's law). 3. I tried to solve as: But the answer is wrong, can anyone help me please, and...

For a particle undergoing a constant velocity circular motion. I thought friction always acted in the direction of motion which would be in the tangential direction.

Hi. The problem is really simple I think, but I feel like the text is wrong even though the result seems to be correct. 1. Homework Statement An object of known mass m (71.5 Kg) is pushed on a [flat] surface with a known friction coefficient of μ (0.272). How much does the object move with a...

Homework Statement A 10 kg rubber box is resting on a concrete floor. A force of 200 N is then applied to this box in a horizontal direction. What is the magnitude of the friction force on the box? Homework Equations This is a question about applying Newton's laws so Fsmax = μs η and η = mg...

How would you find the friction of a box being pushed against a wall with a force of 200N and a weight of 100N?

Homework Statement So, these 2 blocks are connected by a rope. Aluminuim block is 2kg and copper is 6kg. They are kept in motionless state via some kind of mechanism on steel surface. θ is 30 degrees. I was given dynamic and static friction coefficient (Aluminium μs=0,61 i μd=0,47, Copper...

When we put an empty capillary tube in a water container, the water goes up a little bit by itself until the surface tension (ST) force is equal to its weight .This shows that unlike friction, this ST force acts individually . So if we take out the tube out of the container, and drain a little...

Oiy. It is my 6th year teaching physics and early on, I diverged from the textbook (Holt Modern Physics) regarding how they handled "g". To me, it made more sense that "g" was -9.81m/s2 , while the text handled it as "g" = 9.81 m/s2, and negatives are assigned directionally. Overall, my...

Homework Statement This is a real world application. I am posting it here to follow the guideline for any "coursework-like" questions, but since I have no formal training, I'm not sure what category this would actually fall under. Any recommendations for a more specific posting location would...

Background: I'm building a treadmill for VR that moves in any direction but I need to figure out if it's worth building or not because of a problem a friend pointed out to me. Problem: I need to figure out if there's a way to calculate how hard it would be to move this tread by walking on it...

Homework Statement A body of mass "m" is let go from on top of a surface A, where it slides down to B(without friction). From that point on, it displaces itself on an horizontal surface 5 meters away from B, where it stops at C. Being "m" a mass in kg "h" in meters and g = 10 m/s^2 The value...

Ok...Suppose I try to roll a ball to the right...Its surface at the point of contact with the floor would be deformed, which would cause some ''rolling friction'' to the left, which in turn would cause some clockwise torque(rolling motion) in the ball...(please point out if something is wrong in...

Homework Statement A force of friction of 3.2N acts on a 1.1Kg puck while it is sliding along a horizontal surface. If the initial velocity of the puck was 7.5 m/s, how far will the puck travel before coming to rest? Homework EquationsThe Attempt at a Solution The answer is 9.7M. Tried...

Homework Statement The two blocks ##(m=16 kg)## and ##(M=88 kg )## , are not attached to each other.The coefficient of static friction between the blocks is ##μ=0.33##, but the surface beneath the larger block is frictionless.What is the minimum magnitude of the horizontal...

Homework Statement Two blocks,in contact,slide down an inclined plane ##AC## of inclination ##30^°##,The coefficient of kinetic friction between the ##2.0 kg## block and the incline is ##μ_1=0.20## and that between the ##4.0kg## block and the incline is ##μ_2=0.30##. Find the...

Homework Statement A 1000 kg boat is traveling at 100km/h when its engine is shut off.The magnitude of the frictional force ## \vec f_k## between boat and the water is proportional to the speed v of the boat:##f_k=70v##,where v is in meters per second and ##f_k## is in Newtons.Find...