Coefficient Definition and 1000 Threads

I need an expert to verify equations about the coefficient of kinetic friction.

Hello all, I am trying to solve this one: John has n friends . He wants to invite in each evening (365 days a year) three of his friends for dinner. What should be the size of n, such that it will be possible not to invite the same triplet twice ? What I did was: \[\binom{n}{3}\leq 365\]...

Summary:: Does the surface area of a parachute affect its drag coefficient? If so, how? I have been trying to figure out the effect of surface area on the drag coefficient of a parachute. I have designed a lab in which parachutes of different surface areas are dropped and the terminal velocity...

If I orient my refrigerator such that the condenser coils at the back are facing a glass door (least insulation in room, cold outdoors) will CP increase? CP=Qc/(Qh-Qc) so Qh-Qc will be smaller thus CP larger. Could this damage refrigerator?

I know you find the static friction of an incline by raising it until it begins to move and then measure the tangent of that angle, but I'm not sure how I'm supposed to show a relationship or create a procedure based off that.

I don't know how solve this.. [User has been reminded by the Mentors to show their work on schoolwork problems]

hey, i was looking for information on friction coefficient of marble on plastic and iron on plastic. if you know these values i'll be very glad! thanks in advance

Fn = 53 X 9.81 X cos 22 Fnet = 524 – 53 X 9.81 sin 22 + μ X 53 X 9.81 cos 22

> A Ti02 film of index 2.5 is placed on glass of index 1.5 to increase the reflection in the visible. Choosing a suitable value for wavelength, how thick a layer in microns would you want, and what reflectivity would this give you? My question is about the last question presented above...

The solution in my textbook says that for b, us = 0.234. However when I use the formula above I get 0.2364 which I feel like is too far off. Something must have gone wrong... Any help would be much appreciated! Thanks :)

Hi, I just found this problem and was wondering how I might go about approaching the solution. Question: Given three random variables ## X##, ##Y##, and ## Z ## such that ##\text{corr}(X, Y) = \text{corr}(Y, Z) = \text{corr}(Z, X) = r ##, provide an upper and lower bound on ##r## Attempt: I...

I think I calculated part a correctly by extracting the cp (specific heat) of water from the table which is 4.188 Then calculated Q_dot by simply using the equation Q=m*c*deltaT=10.47kW But I am stuck at part b, I know that the heat extracted from the water is the same as Q_L (rate of heat...

I know k is thermal conductivity but my teacher never told me about effective coefficient of thermal conductivity. I tried googling and found: $$k_{effective}=\frac{\Sigma{k.A}}{\Sigma A}$$ But I don't know the area to used that information. Is there another approach to do this question? Thanks

So firstly, I don't understand if the mass flow rate is for steam or for water. If it is for water, I know I can find the heat transfer rate using equation:Q=mcdeltaT. But then I don't know how to find h (the average heat transfer coefficient) because I don't know the surface area (As). I can...

I drew a free body diagram for the crate. I have normal force going up, weight down, static friction force to the left and the force of the crate sliding to the right. I'm assuming the truck is moving to the left. I have Fnet=0 because the crate is not moving, so the forces are balanced. I...

Hi ##\mu=\frac{\alpha TV–V}{N c_P}##. So, firstly, I have to calculate ##\alpha## and ##c_P##. So ##\alpha=\frac{1}{V} \frac{\partial V}{\partial T}## at constant ##P##. I can write ##U=PV##, then I replace it in the equation of ##T##, solve for ##V## and then I differentiate with respect to...

Please could someone point me in the direction of an equation/ book I can use to obtain the convection coefficient for steam in a heating jacket. Steam is at 1 bar pressure. I think I need to use a dimensionless number. Thanks

Hello I,d like to find or to calculate Rolling resistance coefficient on sand tyre 37/12.5 R37. Thanks for your help

Confused how to approach problem after making a free body diagram and finding the length of the inclined plane

I want to make a video game about snipers and I would like it to have proper bullet physics, not something very accurate, but with "credible" bullet physics. So I need to implement a simple trajectory solver. I thought of taking into account just the gravity and turbulent air drag. The...

In this part of the lab we pushed a block on a flat table and let it slide until it stopped. So it is decelerating with no force being applied to it while moving. In this case acceleration is negative. The only force acting on it is kinetic friction. Therefore I have come up with the following...

Assume that I have the Lagrangian $$\mathcal{L}_{UV} =\frac{1}{2}\left[\left(\partial_{\mu} \phi\right)^{2}-m_{L}^{2} \phi^{2}+\left(\partial_{\mu} H\right)^{2}-M^{2} H^{2}\right] -\frac{\lambda_{0}}{4 !} \phi^{4}-\frac{\lambda_{2}}{4} \phi^{2} H^{2},$$ where ##\phi## is a light scalar field...

Hi, I started to think about the drag coefficient of a sphere. At high Reynolds number Cd drops of suddenly when the boundary layer separates. If the Reynolds number is increased further, Cd increases with increasing Re. (I'm thinking about what is referred to as "post critical separated flow")...

The coefficient of determination is 83.0 \%. Provide an interpretation of this value. $\begin{array}{rrrr} x & y \\ 12.17 & 1.88 \\ 11.70 & 1.82 \\ 11.63 & 1.77 \\ 12.27 & 1.93 \\ 12,03 & 1.83 \\ 11.60 & 1.77 \\ 12.15 & 1.83 \\ 11.72 & 1.83 \\ 11.30 & 1.70 \end{array}$ here is my desmos plot...

I tried to solve the task in different ways, I had different ideas but none of them led me to the correct solution. I would be grateful if someone would explain at least the initial part of the task to me. True answer: 10-3K-1

https://www.physicsforums.com/attachments/277763

Hello everyone, Once I got through the VDW state equation I came to the expression of the thermal expansion coefficient. When I place the values I get an illogical answer. Is there a problem with the units? (Please ignore the values) Thanks. This is the unit equation I get to and get stuck:

Hi, I'm looking to find a very very basic model to calculate the heat transfer coefficient in a tube with given heat power exchanged ##Q##. The fluid inside the tube starts sub-cooled (##T_{in}## is known) but exits the tube with a quality of steam around 0.15 (pressure is supposed constant)...

Summary:: Initial value problem Solve the given initial-value problem differential equation by undetermined coefficient method. d^2 x/dt^2 + w^2 x = F sin wt , x(0) = 0, x'(0) = 0 I get the sol = C1 cos wt + C2 sin wt, but i always get 0 when I plug into the equation, anyone can help me...

Variation coefficient is calculated by And the very definition of poisson distribution is that $$\mu = \sigma $$ So how would any other value but 1 be a possible?

Consider the following scenario. A material has the E-k band scheme as shown in the figure (extended scheme of zones). Could anyone give me a suggestion regarding the following : Electrical character of the material with the temperature. Sign of the Hall coefficient. Sign of the effective mass...

I have found the value for the full width at half maximum line profile width , I know the the density of the upper lasing state for the helium neon laser is 10^18 m−3, and I am assuming I have to use dN_2/dt = -A_21N_2, which I can turn into N_2(t)=N_2(t=0)exp(-A_21*t), and I have calculated...

I want to compare diffusion of a tracer gas with a low exposure limit (e.g. isoflurane) to the advection of air by a ventilation system. When will diffusion exceed advection? I can't make sense of diffusion constant to compare transfer rates or velocities. At room temperature the diffusion...

So, it's a long way to the solution, but I'm finding it difficult to find a starting point. I'm going to say that as a first step, I should find what the value of the stream function ##\psi## is, at the surface. In order to do this, I need to use the following equation: ##F=\phi+i\psi## If I...

So I think I may be overcomplicating this problem but I realize that in order to find the x^3 term it will be the product of the two binomials, ie. x^1*x^2=x^3. The coefficient of x^3 will be the coefficient of x^1 in the first bracket multiplied by the coefficient of x^2 in the second bracket...

Hi guys, for my final high school project I want to create a simulation in Unity (A game engine) in which you should be able to make an airplane fly with extremely accurate physics. In the regular formula for Drag is: Fd = 1/2 * ρ * v^2 * Cd * A. I can get all these things except the Drag...

I am wondering if there is a typo in my textbook. Please see the attachment. The textbook says "...keeping only the lowest term in x = v/c." I am wondering if it should be "x = v/(nc)," as I circled in blue on the left side. It is a binomial expansion of the denominator. Shouldn't x be v/(nc)...

"Calculate the gradient (or slope) of the line and use this and the equation above to calculate the value for the viscosity, η. You MUST use the gradient to calculate the viscosity." here are the results: I'm not sure if it's just me who finds this confusing

For a random variable Ti, SD (Ti) / E (Ti) ≤ 1 with SD (Ti) = (Var (Ti))1/2 and E (Ti) the expectation of Ti and Var (Ti) the variance of Ti. My question now is whether the following property then also applies. For any variable T, SD (T) / E (T) ≤ 1 where T = T1 + T2 + ... + TN and where...

Hey! 😊 Let $\mathbb{K}$ be a field, $1\leq n\in \mathbb{N}$ and let $V$ be a $\mathbb{K}$-vector space with $\dim_{\mathbb{R}}V=n$. Let $\phi :V\rightarrow V$ be a linear map. The following two statements are equivalent: - There is a basis $B$ of $V$ such that $M_B(\phi)$ is an upper...

I would like to fully understand two parameters involved in convection heat transfer systems. I have read the document https://fenicsproject.org/pub/tutorial/sphinx1/._ftut1005.html, and I am interested in the parameters ##r## and ##s## in eq. 69. As far as I understand, when one solves the...

A C of L curve for a particular airfoil is calculated based on what? I know AOA is a part of it but is there a formula for CL itself? For example... CL= L / rho * 1/2 * V^2 * S Which is fine. but... L = CL * rho * 1/2 * V^2 * S gets a value for CL from somewhere, right? I assume it’s...

Not sure if I did something wrong but I am getting two different coefficients of friction for each velocity.

I am trying to add the magnus effect to a golf simulator program but am getting stuck on the coefficient of lift. What are the units I should be using in these calculations? The rest of my program I use SI units. But I seam to get weird results when using them with these equations. Spin factor...

What I need help with is how I would start.. I can say p(X, Y) = (1,0) = 1/4, and same for the other 3 coordinates. P = 0 for all other coordinates. This doesn't give me anything to work with though. C(X, Y) = E(XY) - E(X)E(Y) What is XY? I don't even know what X is.

We know that, Conduction Heat Transfer Q = KA(t2-t1)/thickness K is the coefficient of thermal conductivity. If T2 = 1020°C and T1= 22°C also consider we know A and thickness value. K depends on temperature. K varies with temperature. For all the materials we have a tabular data of K for...

Equations I think may be relevant:

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...

I want to solve the following system of equations ##M_{1} = f_1+f_2+m_1+m_2\ \ ;\ \ M_{7} = f_1+f_2+s_1+s_2\ \ ;\ \ M_{13} = m_1+m_2+s_1+s_2## ##M_{2} = f_1+f_3+m_1+m_3\ \ ;\ \ M_{8} = f_1+f_3+s_1+s_3\ \ ;\ \ M_{14} = m_1+m_3+s_1+s_3## ##M_{3} = f_1+f_4+m_1+m_4\ \ ;\ \ M_{9} = f_1+f_4+s_1+s_4\...