Coefficient Definition and 1000 Threads

Please could somebody explain how the coefficient of static friction can be quoted as a constant in tables etc? \mu_s = F_s/ R In most cases the reaction force is constant but as I push the box harder the friction force increases. Is \mu_s actually the coefficient of limiting friction? Or...

Hello, I am new to Aerodynamics and am having trouble understanding what exactly the roll damping derivative is. The roll damping derivative is a measure of the change in rolling moment coefficient with respect to nondimensional roll rate and is usually negative. Does that mean a glider...

Homework Statement A crate of bananas has an initial speed of 4.2 m/s2. It slides across a floor, traveling 6.0m before coming to a stop. Find the coefficient of kinetic friction between the crate and the floor. Homework Equations Fnet=ma v2=v02+2aΔx The Attempt at a Solution...

Homework Statement You are building a device for monitoring ultracold environments. Because the device will be used in environments where its temperature will change by 211°C in 2.99s, it must have the ability to withstand thermal shock (rapid temperature changes). The volume of the device is...

Homework Statement When the temperature of liquid mercury increases by one degree Celsius (or one kelvin), its volume increases by one part in 550,000. The fractional increase in volume per unit change in temperature (when the pressure is held fixed) is called the thermal expansion coefficient...

Hi Is the drag coefficient for a particular object the same in different mediums? Say we have Cd = 1 in air for one object, is Cd the same for this object in water?

Hello Fellow Forum, How would you calculate the coefficient of friction for sandpaper? I'm testing mechanical resistance of a bioplastic, and I'm going to attach the bioplastic to different weights, and then rub sandpaper over the bioplastics. The one that breaks will be used to find...

This question relates to rate constants of transition events. The transmission coefficient κ reduces the value of the rate constant compared to the transition state theory (TST) value. I understand κ to be defined as the probability that a reaction coordinate q will proceed to product given that...

I have a bunch of noisy data points (x,y), and I want to model the data as y = ax2 + bx + c + noise where noise can probably be assumed to be Gaussian, or perhaps uniformly distributed. My data is firmly inside of an interval and I'm only interested in modeling correctly inside of this...

What is the minimum force needed to overcome static friction on a block whose normal force is 5.2N and has a coefficient of static friction 0.34? A desk is pushed with a constant velocity along a floor. If the mass of the desk is 25kg,and the force required to keep the desk moving is...

Is is possible to get the Spearman coefficient on a TI 84? Not the Pearson, the Spearman.

A 20 Kg. mass slides up on an infinitely long inclined plane (that forms an angle of 30º with the horizontal) with a velocity of 12 m/s. It's known that the mass returns to the starting point with a velocity of 6 m/s. Find,μ, the coefficient of friction between the plane and the body. This is...

It is well known that the evolution of the input reflection coefficient, ρ, of a LTI causal passive system with frequency, f, always presents a local clockwise rotation when plotted in cartesian axes (Re(ρ), Im(ρ)), e.g. in a Smith chart, as shown in the attached figure. It must appointed that...

Show that $$ \begin{align*} \sum_{n=0}^\infty \binom{2n}{n}^3 \frac{(-1)^n}{4^{3n}} &= \frac{\Gamma\left(\frac{1}{8}\right)^2\Gamma\left(\frac{3}{8}\right)^2}{2^{7/2}\pi^3} \tag{1}\\ \sum_{n=0}^\infty \binom{2n}{n}^3 \frac{1}{4^{3n}}&= \frac{\pi}{\Gamma \left(\frac{3}{4}\right)^4}\tag{2}...

Homework Statement Measurements of XRay scattering from a metal are made. The bragg peaks are θ = 53° and 48° for temperatures of 300K and 1272K. What is the linear expansion coefficient? Homework Equations linear expansion coef is given by (1/L)(dL/dT) Bragg equation (differential...

Homework Statement Does Coefficient of Performance for refrigeration cycle depend on refrigerant used? In reference to vapor-compression cycle Homework Equations COP = \frac{1}{\frac{T_{H}}{T_{L}}-1} The Attempt at a Solution I am split in my answer to this question. I...

I am working on a motorcycle dynamics problem. I have written the equations of motion in matrix form in MATLAB (and mathcad). It is a 4 degree of freedom system, so I have a mass, damping and stiffness matrix all 4X4. I am able to find from these matrices the natural frequencies, and damping...

In a recent lecture,I learned that the friction coefficient "mu" between the tire and road surface is determined experimentally by using a graph. i.e a graph between the longitudinal tire force and the longitudinal slip. Well,how did engineers emperically arrive at such a graph in the first...

Homework Statement I'm trying to derive the coefficient matrix (a) of a parabolically terminated cubic spline. This is the matrix of coefficients ##a_i \rightarrow a_n## where n is the number of data points provided. With this matrix you can find all the other coefficients (b and c) that...

As you can see, around Reynolds number of 5 105 the transition occurs for a smooth sphere. However, why is it that after this transition that the drag coefficient increases at turbulence?

1. A 4.0 m long bar is suppotred by a string as shown in Figure 10-61. What must be the coefficient of friction between the bar and the floor if the bar is on the verge of slipping Image: 2. τ = r*F*sinθ or τ = r*F, where the force is perpendicular to the radius. Summation of...

Homework Statement I know the diameter is 30 m and the radius is 15 The period for one revolution I suppose is some multiple of 7.03 Homework Equations The Attempt at a Solution I couldn't think of an equation where friction was involved where rotational motion was concerned. I...

Hello, I was reading somewhere about how to control Rudders in RC planes. The basic equation here is the drag equation: F=0.5*ρ*v^2*C*A (take ρ=1Kg/m3) where v is the velocity, C is the Drag coefficient of the control surface (Rudder in this case) and A is the area. I am wondering if we have...

Hi guys, i need your help to go about his question, Question: $$\text{Show that the coefficient }C_n \text{in the Laurent expansion of }$$ $$f(z)=(z+\frac{1}{z}) \text{ about z=0 is given by}$$ $$C_n=\frac{1}{2\pi}\int^{2\pi}_0 \cos(2cos(\theta))cos(n\theta)\, d\theta ,n\in\mathbb{z}$$

Lets say you have a block on a horizontal surface connected to a pulley and then a weight hanging over the edge. If its not moving then the force applied which is just the mass of the weight x gravity is equal to the force of static friction μsmblockg. So that means μs = the mass of the...

hello everyone. Can anyone please help with following questions? 1. Can coefficient of friction (both static and dynamic) be greater than one? What happens if it is greater than 1 ? 2. Why coefficient of kinetic friction is less than coefficient of static friction and why it decreases at...

I've been told that the coefficient of restitution is a little like friction; it's a measure of how elastic a collision is between two objects, it's not an individual property of each object itself. Now let's say you have two balls bouncing on the ground. Ball 1 has a coefficient of...

A box slides down a 30° ramp with an acceleration of 1.20 m/s^2. Determine the coefficient of kinetic friction between the box and the ramp ok so the only equations I know are μk= Fk(kinetic friction)/Fn(normal) and that Fn=mass x gravity so i don't know how to get Fk or mass... so help on...

1. Here is the problem http://i.imgur.com/WH0Z4ko.png So I've set up a Free Body Diagram and I think I have it right. I have the two Forces of Weight (8.82N and 21.27N), the force of 12.8 that is pulling the .9kg box, and then the Force Normal (just the opposites of the two Forces of...

Homework Statement There's no specific problem statement but I have to explain how I would find out the coefficient of kinetic friction given the angle (θ) of the inclined plane and mass of the object sliding down, nothing else. Homework Equations ƩF = ma μk = Fk (kinetic friction) / Fn...

Hello, For my Classical Mechanics Lab, my fellow students and I are to calculate the coefficient of air-resistance of several objects dropped from the roof of our science building. We are assuming that the air-resistance is linear in nature. The first method by which we calculate the drag...

Homework Statement Find the coefficient of x8 in the expansion of (x2-3)7 Homework Equations This one: (n n-j) an-jxj The Attempt at a Solution Hi! Well, I know that x= x2 a= -3 n= 7 and apparently, j=8. This is what confuses me. n-j is a negative number.. how would...

Homework Statement A block is projected up an inclined plane that makes an angle θ to the horizontal. It returns to its initial position with half its initial speed. What is the coefficient of kinetic friction between the block and the plane in terms of the angle of the incline...

Homework Statement You are to lower a safe of mass 260kg at constant speed downs skids 20.0m long, from a truck 2.0m high. a) If the coefficient of friction between the safe and the skids is 0.25, do you need to pull the safe down or hold it back? b)How great a force parallel to the skids is...

Homework Statement I have a box on a horizontal plane. Given data: mass = 0.25kg height of object = 14 cm width of object = 9cm Calculate the coefficient of static friction. Homework Equations μs = Ff/N (N is the normalforce) F = Ff = μ*N mg = 2.45 Newton The Attempt at a...

Hi all, This is my first post here. As a bit of background I have a keen interest in mathematics, but I'm not necessarily strong in it... Today I was working with a dataset that models difference in elevation values (dH) over time (x). I have approximately 20 samples, of which each dH value...

Quantum -- Find the formal expression of the coefficient cn(t=o) Hello everyone, I'm really stuck on the first question of an exercise, so I can't start! :cry: Homework Statement ψ(x,t) a wave function normalized and solution of Shrodinger equation for a given potential. I the...

Hello physics forum! I come to you with a binomial coefficient problem I am stuck on. Here is the question 1. Suppose an airport has three restaurants open, Subway Burger King and McDonalds. If all three restaurants are open and each customer is equally likely to go to each one, what is the...

A road vehicle equipped with mechanical wheel brake e.g drum or disc brake ,driving at a speed of 100Km/hr is braked to a stand still with a deceleration of 1G (3.2m/sec^2),How large must be the coefficient if friction between wheel and road at least be to enable that. Options: 1)At least...

Homework Statement I need to calculate molar extinction coefficient for Albumin at 280nm. Homework Equations A=ε*c*L ε=A/(c*L) But since L=constant, I can just say ε=A/c The Attempt at a Solution The given molecular mass of albumin is 66,5kDa, which equals 66500g/mol. I do...

Homework Statement A man of mass m is applying a horizontal force to slide a box of mass m' on a rough horizontal surface. It is known that the man does not slide. The coefficient of friction between the shoes of the man and the floor is ##\mu## and between the box and the floor is ##\mu'##...

Hi, Will I have a higher slipping force / torque by increasing the width of my brake shoe and drum? Though my instinct says it is possible, textbook says it's only the coefficient of friction that controls the slipping force. Can you pl help me understanding this? Thanks.

Homework Statement a block with a mass of 0.310kg at a constant velocity , calculate the coefficient of kinetic friction on an incline plane Homework Equations f=ma fg=mg fparallel= mg* sin30 degreesThe Attempt at a Solution I found the FN which is 2.60 and the f parallel to be 1.52. i...

Lately, I have conducted an experiment where I dragged various circular cylinders through water in order to find the resistance, and hopefully also the drag coefficient. It seems to me that this coefficient is dependent on what is called the Reynolds number. Using some sources, I can easily find...

A hockey puck on a frozen pond with an initial speed of 12.3 m/s stops after sliding a distance of 198.9 m. Calculate the average value of the coefficient of kinetic friction between the puck and the ice. So I started with finding the acceleration. I divided 12.3m/s by 198.9m then took the...

Homework Statement Prove that ##\binom{-1}{k}=(-1)^k## The Attempt at a Solution Using induction on ##k##, ##\binom{-1}{0}=1## which is true also for ##(-1)^0=1## Assuming ##\binom{-1}{k}=(-1)^k##, then ##\binom{-1}{k+1}=(-1)^{k+1}## Indeed when ##n=-1##, we can write...

So I've been stuck on this type of question, please help! You are pushing horizontally on a 3.0 kg box of wood, pressing against a wall. If the coefficient of static friction is 0.60, how much force must you exert on the block to prevent it from sliding down? Homework Statement What is...

Dear Everyone, I have a problem to be solved now. how to calculate the symplectic group SP(3,R) non-compact induced by the SU(3) group? Any reference provided will be appreciated.

Homework Statement A steady stream of 5 eV electrons impinges on a square well of depth 10 eV. The width of the well is 7.65 * 10^-11 m. What fraction of electrons are transmitted?Homework Equations The following equation for the transmission coefficient, T, is given: T = [1 + \frac{V_0 ^2...

Hey all, I'm trying to simulate a simple chip-heatsink situation in SolidWorks using their thermal modeling suite. I have found an ideal set of parametric values for the chip to work at a reasonable temperature, but I need to figure out what the convection coefficient means in terms of air flow...