Coefficient Definition and 1000 Threads

Hi There Does anyone out there know a good estimate or any real values for the total heat transfer area for the hot and cold sides of a domestic refrigeration system? i.e. the sum of the areas of the evaporator and the condenser. For the Evaporator: QL=UL.AL.(TL-T1) AL=heat transfer...

I am looking for an exact value of absorption coefficient of aluminium for microwaves, but I can not find it in the internet. Anyone knows where I can find it?

Homework Statement This problem is from a homework assignment. The professor says that the the ping-pong ball will go up if the cd = 0 and will go down if the cd is much larger than one. Is this logic correct? I keep thinking about how if an aerodynamic car is pushed by wind, the car...

Homework Statement ##| \ X \in \mathcal P(\{0,1,2,3,4,5,6,7,8,9\}) : |X|= 4 \ | = \ \ ?## Homework Equations There's no wording in the exercise , just what I wrote above.If I understood correctly , they asked me to find the cardinality of the set of all subsets of {0,1,2,3,4,5,6,7,8,9} that...

Homework Statement This one is trickier than the problem in my other thread in my opinion.Twenty-one people are to be divided into two teams , The Red Team and the Blue Team.There will be 10 people on Red Team and 11 people on Blue Team.How many ways to do this? I am not sure how to solve...

Homework Statement A department consists of 5 men and 7 women.From this department you select a committee with 3 men and 2 women.In how many ways can you do this? Homework Equations Since the "overall set" (the entire department) is composed of both men and women and each has a specific...

Homework Statement I am conducting an experiment to determine the coefficient of static and kinetic friction between 2 objects I've arbitrarily chosen. I have a block and a plank of wood. I have been raising the plank to an incline to determine at what angle the block will begin sliding. I...

Hi I was looking at how to calculate the GINI coefficient and saw two different statements from two websites. Statement 1: It has been shown that the sample Gini coefficients defined above need to be multiplied by in order to become unbiased estimators for the population coefficients...

https://www.khanacademy.org/math/probability/regression/regression-correlation/v/r-squared-or-coefficient-of-determination Homework Statement So, when determining how effectively a best-fit line describes the variance of a given set of measured data, the Coefficient of Determination is the...

Can someone please look at this and tell me what's going on here? I'm trying to understand the coupling coefficient k between two wire coils some d distance apart. I found this but I am lost! Please help!

Hello, I was competing calculations for a simple machine lab, and I got a different mu_k for 3 separate inclines of 20,30 and 40 degrees. But a question asks says ,"explain why the coefficient of kinetic friction should be independent of the inclination angle of the inclined plane." How do I...

Say if an iron disk slides down a non ferromagnetic conductor ramp and we get a certain time. And then we have an iron disk with the same mass but MAGNETIZED slide down the same ramp and get a longer time (because of of magnetic braking). The calculated acceleration of the MAGNETIZED disk will...

Physics coefficient of friction question! A 17kg box is being pushed by a 150N force. If the box is accelerating at 2.3m/s2. What is the coefficient of friction on the ground?FNet=μFn Fn= 9.8x17= 166.6N How can I find the fnet?

Hello, I am stuck on this question, I don't understand what to do. Any help would be great! I know that I have to use Newton's Second Law in the x and y directions. Greezy is pushing a very large crate of 50 kg across the floor at a constant velocity with a force of 200N. He is pushing on...

Reading in Russian sources I see they use ballistic coefficients such as these: BC = 3.0 kg/m^2 or alternatively BC = 3.0 m^2/kg That's quite different than the usual G1, G7, etc. Given a certain muzzle velocity, how do I use that to calculate velocity at some point downrange?

Homework Statement f(x) = 1, 0<x<1 Extend f(x) t generate an even function P(x) and find Fourier coefficients Homework Equations an = 2/T ∫ P(x)cos(2nx/T) dx The Attempt at a Solution P(x) = 1, -1<x<1 0, -2<x<-1 , 1<x<2 even function so b0 = 0 Average of P(x)...

Homework Statement I´ll show the problem with a picture: Homework Equations M=rxf Sum Forces = 0 Sum Moments= 0 The Attempt at a Solution I recognize that I am completely lost with this problem, so I´ll try to analyze every force acting on every body to show where are my doubts. When...

Homework Statement A 3 kg block slides down a 30 degree inclined plane with constant acceleration of 0.5 m/s2. The block starts from rest at the top. The length of the incline is 2 m. Homework Equations Vf^2=Vi^2 +2ad velocity is 1.414 Fg=3 x 9.8=29.4 Fn= cos(30) (9.8 x 3) = 25.5...

I want to solve a depressed quartic: ax^4 + bx^2 + cx + d = 0 Assume |a|\ll |b|,|c|,|d|. I would like to find the solutions by expanding around the solution to the quadratic. If you try to solve in, say, Maple, and expand around a in a series you get something that blows up. That seems silly...

Hey all, I'm trying to design a clamp that has to hold onto a hollow carbon fiber tube, approximately 2.5 inches in diameter. The clamp will be bearing a 15-20lb load. The carbon fiber will be at angles from 20-70 degrees from a vertical axis. I'm curious if there is a polymer that can be...

Homework Statement Homework Equations r=\frac{S_{xy}}{S_{x} S_{y}} S_{x}=\sqrt{\Sigma(x-\bar{x})^2} The Attempt at a Solution I have calculated the value of Sx several times and I got 43.3 but the answer key said that Sx = 11.2 1. Is my formula correct? 2. If yes, is my...

The coefficient of variation tells us about the consistency in the data. I know that the lower the coefficient of variation is, the higher will be the consistency in the data. What I don't understand is what is being meant by 'consistency' here. Could someone please explain that?

Homework Statement You do 2.2 kJ of work pushing a trunk at a constant speed 3.1 m along a ramp inclined upward at 22 degrees. What is the frictional coefficient between the trunk and the ramp? Homework Equations W = F*d Ff = μmg * cos(θ) Fg = mg * sin(θ)The Attempt at a Solution To find the...

Okay I got to wonder about this: Why is the multinomial coefficient independent of if you start by taking out n1, n2, n3 etc. or n2,n1,n3 or n3, n2, n1... etc.. I mean intuitively from actually doing the combinatorics by counting it seems obvious that the order should not matter. But can this be...

what is the max free air heat transfer coefficient(film coefficient)? at 1000 c? i have a object that is at 1000 degree c by applying 900watt. i model it solid edge and apply heat generation load of 900 watt, from what i research air convection is 5-25 w/m^2/k. but when i apply that in the...

let say a cylinder(steel) is 6 cm diameter and length of 3.5 cm length. and is heated to 1000 degree c. in a room of free air and room temperature of 20. will convective heat transfer dominate? it radiation is negligible? what would the convective heat transfer be? what power(watt)...

whats would be typical value for free air convection heat transfer coefficient at high temperature of 1000 degree c? let say i have a vertical cylinder of diameter 5 cm and 3 cm high. and i heat it to 1000 degree c. the room temperature is 20c . what would the convection heat transfer...

Homework Statement A child's slide is flat, 5 meters long, and sloped down so that the top is 3 meters higher than the bottom. A child slides down, starting from rest, and has v = 6 m/s at the bottom. Find the coefficient of kinetic friction, μk is: Homework Equations F=ma f=μkFN...

Homework Statement In Attachment Homework Equations The Attempt at a Solution Second Attachment. - I have only attempted part (i) so far, because I am not sure if I am doing it correctly. I was thinking since the value of the latent heat of pentane is given, surely it has to be...

Homework Statement A small 15 kg cardboard box is thrown across a level floor. It slides a distance of 7.0 m, stopping in 3.3 s. What is the coefficient of friction between the box and the floor? Homework Equations The Attempt at a Solution I didn't know how to do it. I just...

Homework Statement I need to approximate the thrust given by a propeller blade that are plastic and around 10-15cm in diameter but I am not sure what the coefficient of lift (or coefficient of thrust because they are the same thing?) is. For example, a propeller blade may look like this...

Can we assume that the coefficient of drag of a car model is constant using one of the values from: http://en.wikipedia.org/wiki/Drag_coefficient The reason I ask this is because the coefficient of drag of a car varies with velocity. So wouldn't it change depending on how fast the car is...

Homework Statement Use the binomial series to expand the function as a power series. 1/(2+x)3 I have attached an image. I understand until the end of the second line. I don't see the reasoning used to follow through to the third line. the (-1)^n is because the sign alternates becoming...

Find an expression that is identical to \sum_{k=0}^n \binom{3n}{3k} According to Wolfram, the correct solution to this is: \frac{1}{3} \left(2(-1)^n + 8^n\right) But I'm not sure which identities of the binomial coefficient I'm supposed to use to prove this. Can anyone give me some...

Homework Statement A wheel has a radius of 0.4m . The engine exerts a torque on the wheel of 290 Nm. FInd the coefficient of friction. Homework Equations T=RFsin T= Angular acceleration * Inertia (1/2MR^2)? The Attempt at a Solution My friend asked me this question, but I feel...

Let 'x' and 'y' be two random variables with zero mean. We find that 'x' is related to 'y' with a correlation coefficient 'c'. Now let us say we are splitting 'x' into correlated term 'xc'and uncorrelated term 'xu' Then we have x= x_c + x_u \\ \overline{x^2}= \overline{(x_c +...

1. A 3kg block slides down a rough plane inclined at an angle of 27 degrees. If the acceleration of the block is 2.5 m/s/s find the coefficient of kinetic friction. 2. solving for components Force Net = M x A forces in the y direction: Fn - Fg cos 27 degrees = 0 forces in the x...

Okay, so now I've lost all confidence in myself. I've had a lot of issues calculating the reflective coefficient for a glass slab and a thin film solar cell. I know this method isn't perfect, and not as good as experimental data (which, if anyone here can supply, I'd be happy to take it)...

Homework Statement A small ball is placed at the edge of the top step of a flight of steps. Each step has identical dimensions. The ball is kicked horizontally, perpendicular to the edge of the top step. On its first and second bounces it lands exactly in the middle of the first and second...

Hi there, I am doing a project modelling and simulating a gas engine waste heat recovery system using an organic rankine cycle. As part of this project I would like to size the surface area of a heat exchanger (if only roughly). I have found the appropriate formula using Q = U.A.LMTD and...

How many numbers of 6 digits which have exatctly the digit 1 (2 times), digit 2 (2 times), without zero, are there? The book post this solution: \frac{6!}{2!2!}*\binom{7}{2} + \frac{6!}{2!2!2!}*7= 4410, but I'm trying to find an explanation for this result.

Hello I'm new here and to be quite honest not sure if I'm posting this in the right section, so apologies up front if I have this wrong. Basically I was wondering if anyone has any idea on why the dynamic coefficient of friction for aluminium on aluminum is greater than the static coefficient...

What is the coefficient of friction between a 65-kilogram chair and a floor if the chair can be pushed at constant speed with a force of 220 Newtons? My attempt: Given: m=65 kg Ffr (force of friction)=220 N w=mg=(65)(9.8)=637 Fn=637 N μ=? μ=Ffr/Fn μ=220/637 μ≈0.345 Is this right? I...

Homework Statement There are 2 questions in the attachments both with the same scenario I'm having troubles with. Homework Equations f=ma The Attempt at a Solution I tried finding the budging force between the 2 masses and that was about 4. I don't know where to go from there to...

Homework Statement a block of mass 2kg is in at rest on a rough plane inclined at 30°, it is in limiting equilibrium with with a force of 20N applied horizontally (to the ground). Find the coefficient of static friction between the block and the plane.The Attempt at a Solution...

Homework Statement Two objects are connected by a light string that passes over a frictionless pulley as shown in the figure below. m1 = 8.32 kg, m2 = 6.40 kg, and = 56°. When released from rest, m1 accelerates downward at 2.210 m/s2. For this to happen, the coefficient of kinetic friction...

Homework Statement A dump truck loaded with rock has a coefficient of static friction of 0.4, and a coefficient of kinetic friction of 0.2 between the rock and steel tray. If the truck tilts its bed to 25°, calculate the coefficient of static friction on the load. Hence calculate the angle...

A banked circular highway curve is designed for traffic moving at 61 km/h. The radius of the curve is 201 m. Traffic is moving along the highway at 44 km/h on a rainy day. What is the minimum coefficient of friction between tires and road that will allow cars to take the turn without sliding off...

Is there theoretically any way to compute a coefficient of friction (solid on solid) without an experiment between the two materials? Say, some kind of simulation, or perhaps comparing both materials to an intermediary material?

We know that the drag force on an object is defined as: FD = ρ*v2*CD*A/2 , where ρ is the density of the fluid the object is traveling in, v is the velocity of the object, CD is the drag coefficient of the object and A is the surface area of the object. Rearranging the formula to find drag...