Friction Definition and 998 Threads

When a car is moving the velocity of the connection point between the car and the ground is zero. So static friction must be act here ,mustn't it ? But my mentor said ,it is kinetic friction. Which is correct? If kinetic friction, why?

When tires lock, the tires exert a forward force on the ground and the ground exerts a reaction force (kinetic friction) on the tires in the opposite direction. But if the car brakes slowly, the tires are still rotating and so they exert a backward force on the ground, and the ground exerts a...

Could you please help me with this? I guess move of the mass will be determined with kinetic friction.

So I do realise that this problem involves energy, I still wrote equations for forces acting on each block. I will assume coefficient of friction to be ##μ## for convenience. For block 1: ##F - kx - μm_1g = m_1a## For block 2: ##kx= μm_2g## I then wrote an energy equation assuming a velocity...

For this one, am i supposed to use W = change in KE where i calculate work as ((F - friction - mgsintheta) times d), or am i supposed to do the change in -mgh plus Wfriction = change in KE (where if it is in this case, is the friction going to be a negative number?)

Consider a test setup as shown in Image below, where I have a blue object sandwiched between a material inside the container (for eg. sand) and a surface. The container is fixed and the material inside is assumed to not move. Using a force guage, I can measure the peak amount of force...

If I solve a problem of a box sliding down a slope or standing still on the slope, the force of friction is directed up along the slope. What happens if there is a force F pulling the box up along the slope, but it's unknown if it overcomes gravity and box is moving up or it only slows the box...

For reference I'm a high school senior in physics. My thought process: 1) If the force of friction and applied force are equal the object "should" be at rest because the forces are equal (obviously this isn't correct because my professor tried explaining it and I'm not understanding the...

Fastened joints are subject to scatter. It's impossible to get exactly the same value every time. This is especially relevant when using methods that rely on friction such as torque wrenches. The scatter is a combination of the possible differences in friction and the precision of the tool...

I could understand the problem perfectly; however, I do not know how to construct the problem. The problem states that two forces are acting simultaneously on the object, but how could I represent that fact mathematically? I really want to solve it, but I am facing this roadblock, so please...

30 rmp (2 pi) = 60 radians/minute = 1 revolution/sec 0 = 1revolution/s + angular acceleration (t) The only force acting on the toy train at this point is the force of friction. How do I use the coefficient of friction to find angular acceleration? Thank you so much in advance, I literally have...

I first attempted to solve the problem by ##A_{ext} = \Delta E_{mech} = F_{ext}s##. Here, ##F_{ext} = F_{friction}## and ##\Delta E_{mech} = E_{k2} + E_{p2} - E_{k1}##. We obtain then the following equation: $$F_{friction} = (m((v_2)^2 - (v_1)^2))/2h + mg,$$where ##v_1## is the velocity at time...

I thought that the maximum force on the block in the x direction would be the point where the ball crosses the plane of center and thus frictional force would be maximum, and if the block does not slip in that case then it never will slip as the value of force in x direction only decreases...

I think the angular velocity keep increasing on the plane with friction and the translational velocity keep decreasing due to friction while the total kinetic energy is conserved. When it moves to the frictionless plane, all energy converts to translational kinetic energy and it stop rolling...

I've been studying rolling motion for a bit and I realized that there's another hole in my knowledge. Let's say that we have a wheel rolling down an inclined plane. Let's assume that the wheel accelerates down the inclined plane. We can look at the motion of the wheel as if it is moving on a...

I have a problem like above. A is fixed, B is fixed in Y direction and C is placed on B. Theta, h, w and m are known input parameters. If an increasing force is applied on B towards -ve x direction, I want to determine whether C is slide or flip over. Before slide or flip happened, I believe I...

I don't know how to post a picture so I tried my best to describe my question in words. X is horizontal, Y is vertical and there is no gravity effect. There is a block is sandwiched by 2 surfaces (top surface and bottom surface). Both surfaces are fixed in X direction and the bottom surface is...

Hi guys, I am trying to design a brake/locking mechanism to hold up a weight, here is some background; I have a weight 18kg, 170mm away from the pivot point on an arm. A brake compresses the arm at the pivot point. This consist of a M10 bolt compressing a surface area of 1500mm^2 on each side of...

I have asked this question last year (on discord; IPhO server) and I believe I wasn't satisfied by the answer at that time, but I let it go. Today, as I was going through some physics videos on YouTube a video about it popped up. So, I would like to address this issue now. Let's imagine an...

Suppose I have a block of deformable material on a rough surface. I want to have the boundary condition for the stress tensor that takes into account of friction. If the mass of my block is m, and of density \rho and the coefficient of friction is \mu as well as gravity g. The resultant force is...

Hello, I have question about friction at inteface between two component slip occurs at interface when external force bigger than friction force(= normal reaction force * static friction coefficient) After slip occured, component motion stopped and got new static equlibrium state In this...

TL;DR Summary: In Morin 3.7 sliding sideways on a plane I used a completely different method than he did and got the correct answer is my method right The problem statement is as follows I split up the friction force into x and y components derived a diff eq for v_y in terms of v_x then took...

For the first question I thought of using an energy balance, there is friction ##\Rightarrow \Delta E_m = -W_f##. Both at the start and at the end, the block has no velocity. Therefore ##E_{\text{initial}}= \frac 1 2 m_s v_{s,i}^2## and ##E_{\text{final}}= \frac 1 2 m_s v_{s,f}^2##. This means...

The first question statement was under the chapter ##Newton's Laws Of Motion (Without Friction)##. Whereas, the second question was under ##Friction##. The free body diagram for the first question is given as: And the free body diagram for the other question is given as: In the first...

For point one it's clear that I have to use energy => ##ΔE_{AB} = W_{friction}## ; ##\frac 1 2 mv_0^2 - \frac 1 2 mv_1^2 = mgμ_d d## After that there is the path BC, but I don't know how to analyze it from an energetic standpoint. Then after BC the block will now have a different velocity, I...

Across a horizontal pipe with fluid flowing inside, the pressure will drop due to the friction between the fluid and the pipe walls So if for example the fluid flows from left to right and we take 2 points: P1 (pressure on the left) and P2 (pressure on the right) then P1 should be bigger than...

Hello everyone 😊 Let's say, we are having laminar flow in a cylindrical pipe. The fluid in direct contact with the pipe doesn't move (no slip condition), so there is no sliding between the surface of the pipe and the surface of the water. The friction that occurs is actually between this...

I know that the block will move only if the force that pushes him is greater than μs mb g. The only force that can act on the block is the elastic force (Fs) generated by the expansion of the spring, caused by the rolling sphere, that rolls because a force F is acting on the sphere. Then can I...

Ff.x= mv2/2 - kx2/2 umgx= mv2/2-kx2/2 u= mv2-kx2/2mgx =

1) I have a spring on the ground with no friction and the spring is not attached from one end. If I apply a force ##F## and the spring is massless, will it stretch? I think that it won't. But if it has a mass ##m##, will it stretch now? Will it be ##x=\frac{F}{k}##? I don't know, but I imagine...

My query is on highlighted. This was straightforward. I thought that coefficient of friction ought to lie between ##0## and ##1## maybe i need to check that again anyway; ##F_{lim} = 1.5 ×15000= 22, 500 N## Using ## v^2 = u^2 +2as## and ##F=ma## ##22,500 = 1500a##...

Hello, I'm struggling understanding why my answer to this question is incorrect. I know the right answer, but why is this way wrong? I have attached my solution and would really appreciate the help. Thank you!

The context is going down a hill in rollerblades: when people fall and they come to a quick stop (due to not having protective gear and there being lots of friction), they always end up with major injuries, while people with protective pads can sometimes fall and slide for 60+ feet and often be...

Ignoring global warming, the Earth will spin progressively slower. But how will global warming affect this? THEY say, LESS water, LESS slowing. > slowing spin is all about the FRICTION from the action of WATER on the LAND, when the water is gone the slowing of the spin will ceased (or at least...

If the energy itself ignores loss resistance friction and the energy moves forward, can infinity go far at a constant speed?

Hello, I was recently tested on finding the normal force at the base of a ladder leaning against a wall as well as its friction force. So this is the question from memory. Given: θ the acute angle between the ground and the ladder μ as the coefficient of friction between the ground and the...

Good morning! A question from a mere layman, so I hope you won't eat me :D Some time ago I read that every time one solid body makes some contact with another solid body, several billion atoms are lost from the surface of both the first and the second. On the Internet, I once read a post...

How can friction be responsible for all of these: stopping, moving and also turning a car? Does friction actually exist or is it something we assume because we don't know something about motion of objects? I have read a lot of discussions about friction and now it is a cloud of mess in my...

Was surprised by a study recently where we tested 6 samples for pull-off force at a 10% reduction in clamp Torque and noticed negligible shift in results. Is it possible that at higher torque the clamp is deforming the pipe, reducing the surface contact (friction) between the hose and pipe? The...

Is there a typo in this question? Supposing there was no friction, the block would fall until the force of the spring was equal to ##mg = 2 * 9.8 = 19.6##, taking the upward y direction as positive. Since ##F_{spring} = -200y## and ##19.6 = -200(-0.098)##, the block would fall 9.8 cm. It's not...

The answer key claims the answer is -0.9 J. By my math it should be -0.501 J, is that incorrect?

I tried to use the energy route but the acceleration was not a plausible one. It was just way too big.

I am trying to obtain the expression for the potential transmission of torque using friction. I could derive the formula assuming constant pressure between planar surfaces. To have it in LATEX so it is easier to read, this is the expression for the torque transmission using friction...

Good evening, all! Some quick background: I am working on a robot for a competition that strictly limits entry weights to 3lb. Robot speed & acceleration are highly desirable in this competition, so I have been focusing on ways to maximize my entry's performance. Drive motors for these...

So in (a) the answer is just mgsintheta. When doing (b), I got 8.44x10^3N to be the NET force the tractor must exert. Does the tractor not need to overcome its own friction as well? If so, shouldn't the equation be F_tractor = F_exerted - F_friction, and the question is asking for F_exerted...

Easier case: Elevator is at rest. We need to prevent box from free fall so friction should be bigger than "mg".(And they can be equal) When we push with force F we know that the maximum static friction is ##u_sF##. "mg" should be smaller than ##u_sF## or should be equal to it so the minimum...

I used kinetic friction and did mgμ_k=mv^2/r. However, the solution is mgμ_s=mv^2/r. I am confused on why we consider static friction and not kinetic friction, thanks!

My answer for this question is d as every car has the same result for the force of friction since the normal and coefficient of static friction is the same. I cannot find an answer online so can anyone help verify this? Thank you.

I hold my identification card on a low-friction surface by one of its edges. I slightly lean it, and it starts to fall. Before it falls over, I place my finger against the card, and this prevents it from falling all the way over. Then, I withdraw my finger without pushing or pulling the card and...

The thing with this exercise is that I don't think that the question makes sense at all (or, at least, is incomplete). First of all, we don't know if the mass moves with any of those tensions, therefore I cannot know which coefficient apply. Second of all, even if we suppose that the mass is...