Friction Definition and 998 Threads

My question is: given a rigid body which interacts with a surface, what's the direction of the normal force? Because, as the word says, it has to be normal to the surface. But when treating problems of a vertical rod which is slightly pushed and forms an angle ##\theta## with the surface, some...

Hello I've written that homework statement as an example to illustrate my doubt: How can I tell if a force is conservative or not? I've read that, if the curl of the force is 0, it's conservative. But what about the friction force (##f=\mu N##)? Its curl is also zero, but it's not conservative...

if the applied force F >(M+m)g/##\mu## the force of friction between the two blocks should become f=N##\mu## and since the normal reaction will be greater than what it should be to keep the block m at rest with respect to M, will the mass m accelerate upwards. in short,for let's say a very...

when a force of 10N is applied to the 4kg block the force of friction between the two blocks will also equal 10N as the maximum value of friction between the two surfaces is f = N##\mu## = 20N. if you look at this free body diagram f = F = 10N so the net force acting on the top(4kg) block will...

a) ##a_y=\dfrac{\sum{F_y}}{m}=\dfrac{N-mg\cos{\alpha}}{m}=(1-\cos{\alpha})g## ##a_x=\dfrac{\sum{F_x}}{m}=\dfrac{mg\sin{\alpha}}{m}=g\sin{\alpha}## ##a_y=(1-0,866)9,81\;m/s^2=1,31\;m/s^2## ##a_x=(0,5)9,81\;m/s^2=4,91\;m/s^2## How can it be a perpendicular acceleration?; which coordinate system am...

I am trying to understand an excerpt from an article describing the vibrations of a string (eg. guitar/piano) which reads as follows: This is basically the wave equation with Δm representing a small piece of mass from an interval of the string and two forces added to the right side. He...

This problem was from the chapter on Work and Energy so, I thought of using the principle of conservation of mechanical energy. Clearly, the potential energy of the block decreases by mgh (assuming the block has mass m). This energy should have been converted to kinetic energy, but it clearly...

I have a fundamental question that's bothering me. We need rebound force due to friction in order to move forward while walking. On the other hand, we say wheels reduce friction. Then how does it help move forward in the first place? I am confused here :rolleyes:

I have just watched a video lecture about the Tomlinson model (aka Prandtl–Tomlinson Model) which explains the friction mechanism at a nanoscale by analogy with a tip dragged by a spring. The video has prompted me to ask several questions. The spring is dragged over a corrugated substrate, as...

First calc reynolds no. Re Flow = 1.5ms-2 Re = (density x mean velocity x diameter) / viscosity = (1007 kgm-3)(1.5ms-1)(0.1m) / 0.002 Pa s = 75,525 = Turbulent flow I used this chart Here And I am getting friction factor of 0.02 Would you agree with this?

Diagram attached at the endI personally think there's something wrong with this question, and I'd like if someone can tell me whether it's the question that is wrong or my approach. If I attempt the solution thinking that M should be stationary, the solution is simple. 0 - 1/2 mv^2 = -mgh...

I have few conceptual doubts in fluid mechanics. Here is the one I will ask first. I want to understand the force direction acting on the solid liq interface during fluid flow, Let's say a fluid is flowing in a pipe. Now the fluid applies a shear stress at the walls of pipe in the direction of...

Mass is directly proportional to static and kinetic friction and inversely proportion to the coefficient of friction. Material affects the coefficient of friction as well as both static and kinetic friction. eg rough surface will have a higher coeffieiceint of friction

I don't know what to do.

German V2 rocket engine burn was 70 seconds. Rocket speed about 4000 ft per second. Rocket launched straight up for 3 seconds then turned to a 42 degree angle. There is a lot of counterdicting information online about how high up V2 want and how far it flew but that is not the point. Engine...

first, i calculated the kinetic friction: 0.77 x (weight of the 2 boxes x 9.8)= 55.16N then i calculated the angle of the triangle: tan^-1(2.5/4.75)=27.758 then i drew this then i used sine to find out force 3 which is 33.3556 so the final force needed is 33.3556 + kinetic friction=...

In summarize, i have four equations and five incognits. T2,T1,theta,a2,f Need to find one more equation, but i don't know how

Problem statement: Attempt at a solution: 1) There are no relevant moments that need to be drawn in this free-body diagram. 2) There is tension in the chain DE that is pointed away from the truck, i.e. from D to E. 3) There are "ground" reaction forces at points A and B pointed up toward...

Summary:: Having the following dates:

I tried solving this by assuming the acceleration of the truck and block to be the same so the block would stay on the incline. Also, I would assume truck ma = static friction, block ma = mgsintheta... then I solved for a to plug into 1st equation to get 12990 N. Is this correct? I wasn't sure...

I know that taking the scalar product of the harmonic (Laplacian) friction term with ##\underline u## is $$\underline u \cdot [\nabla \cdot(A\nabla \underline u)] = \nabla \cdot (\underline u A \nabla \underline u) - A (\nabla \underline u )^2 $$ where ##\underline u = (u,v)## and ##A## is a...

I can say that the frictional force always against the rolling sphere and the velocity is increasing for the ball. So The dot product F.v keeps on getting more and more negative, so how can the Pf remain constant? Well the velocity increases along the incline and the force of gravity is down...

I am not really sure how to go about this. I have been sick for a couple of weeks and fallen behind a bit. Can anyone help me out please? Thank you

So I started by checking the options.I substituted the value of friction in the equations I got by making free body diagrams.I got different value of Tensions.For 1 and 3 Tension came to be 38 N.For 2 Tension came out to be 42N and for 4 Tension came out to be 40 N. Now I think that I will take...

p man= mv p man = 90 (7) p man= 630 p sled= mv p sled= 100 (0) p sled= 0 p man+sled= 630 + 0 p man+sled= 630 fg man= mg fg man= 90 (9.8) fg man= 882 fg sled= mg fg sled= 100 (9.8) fg sled= 980 fg sled+man= 980+882 fg sled+man= 1862

Friction provides the necessary torque for rolling without slipping.So Rotational Energy must increase.Simultaneously acceleration of centre of mass down the inclined plane is positive so Translational energy also must increase.Overall The Gravitational Potential Energy is getting converted to...

Hi, It is my first message :) I hope you are all fine and safe in these difficult days ! I cannot find the good orientation of the vector of friction. A circle moves in translation to the right and in the same time the wall rotates around A0. A0 is fixed to the ground. There is always the...

My physics teacher said something shocking a few months ago. During a lecture, he asked what would happen if mu of a solid is zero? We answered that the solid will slide very smoothly but he said the Electrostatic attraction would make it hard to slide as the distance between the two surfaces...

hello there, I am wondering if my attempt at a solution for this particular problem correct?? I mean I know that the blocks won't move and the total friction force is 38.95N (at least lesser than that, since that is the maximum static friction). I saw someone attempted the solution but it is...

I think that the answer probably will be yes, but i have a question: Well, with respect to center of mass that's right, but if i choose the axis passing through the contact point, the weight force will produce torque, even without the friction.

Whenever friction exists within a mechanics problem, there must be some dissipation of mechanical energy into thermal energy. However, I'm not sure how we determine which bodies can or cannot possesses thermal energy. Suppose we consider the case of a block sliding down a rough wedge, which is...

Basically, I want to know if my assumptions and workings are correct. This is how I see this situation. First, I'm viewing this body as a series of disconnected points, like I have in this animation I made, modeling purely rolling motion. Modeling the body like that worked in that case, and...

Summary:: How can I measure the friction of a train with its rails and the air. How can I measure the friction of a train with its rails and the air. You can assume that the face of the train is like the picture below. If you need any specifications just let me know

Hello, I have faced a weird problem and would really appreciate any comments. Assume a 2D model e.g. an axisymmetric model, meshed with quad, linear, and reduced integration elements. As you now if a model contains contact, we will get "CSHEAR1" and "CSHEAR2" in outputs. Assuming that the...

Hi guys, First of all I'm sorry for my bad english I'll try to be as clear as possible. I have tried to solve this problem to understand the First Law of Thermodinamics: Q+L=ΔE_t In fact I know L (in the current convention) is the work which the envirorment does on the system but I don't...

I first find the force of friction to be (2)(9.8)cos(65)(.22), then I find the pull of gravity to be (2)(9.8)sin(65). The full equation I set up to be: 0 = kx + force of friction minus the pull of gravity This gives me the wrong answer, 0.44 . My free-body diagram is that kx and force of...

Obviously, friction is not a result of other three kinds of force, and electricmagnetic force is conserved, then why friction is not conserved?

I have been trying a couple of problems with forces and i am not getting the answer, I don't understand what i am doing wrong. Can someone please guide me through this question

I am looking for a rotation devise like that one in this video below (from 00:40 seconds). Does anyone know where to get one, or have any idea about how to create a nice and stable rotation setup for experiments without too much hassle and DIY? A bike wheel won't do, a disk is better, because I...

c = Critically Damped factor c = 2√(km) c = 2 × √(150 × .58) = 18.65 Friction force = -cv Velocity v = disp/time = .05/3.5 Friction force = - 18.65 * .05/3.5 = -.27 N I am not sure if above is correct. Please check and let me know how to do it.

If a block slides down an inclined surface under the presence of the kinetic friction, does that mean the total energy lost by the block is equal to the work done by the kinetic friction? Thanks in advance.

I know that I am supposed to use the equation I wrote, but how do I find the maximum force of static friction and coeffcient of static friction if none of them are given beforehand? I can't have to unknowns in an equation. We then did the same thing, the only difference was then to measure the...

So far, I have this: For Part ii) I know that: mgh = xmgsin(theta), but I don't know how to go further

A recent thread posed the question whether work is done by static friction in the case of an accelerating car. Before I had a chance to reply, the thread was closed on the grounds that the subject was "beaten to death". Undaunted, I am determined to deliver the coup de grâce here with a simple...

From what I read on the internet I found that increase in surface area that is in contact is offset by the reduction in pressure. What exactly does it mean? This is what I understood from the it (but my understanding might be absurd :-p): does reduction in pressure mean that the "hills" or...

(The answer from the markscheme is 26.7)

I'm asking for clarification, but it's my understanding, that of the thread below, and my college physics book Paul A tipler, that when walking or driving a car, the force of friction from the ground does no work. This makes sense in a car becuase the engine/fuel makes the power, driving the...

Hi everyone! Sorry if I'm not able to work through this problem very much myself... I'm a Food Science student, and I'm trying to read an article about ultrasonic cutting when applied to apple slicing. From the papers they reference, the rapid vibrations on the blade reduce the friction...

Hey all, I was recently searching for kinetic friction coefficients, and I noticed that for a reason which is unknown to me, some materials had not been appointed such coefficient. The specific kinetic friction coefficient that I'm looking for is aluminum on greasy/lubricated cast iron. Any type...

I need the coefficient of kinetic friction for movement between greasy aluminium on carbon. It's nowhere to be found on the internet. Thanks in advance!