Coefficient Definition and 1000 Threads

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 Hi, this is not homework or course work, I am a layman and I am just trying to understand an article I have regarding drawbar pull, in particular the pull coefficient (dimensionless) P/W where P is described as "pull (drawbar pull), lb" and W is described as "wheel load...

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...

Period does not depend on amplitude. Correct? I deduced this from the equations for simple harmonic motion: ω=2πf ω=√(k/m)

While writing a physics report, I obtained a data that for balls of rough surfaces, there is a higher drag force and thus the ball can stay stable at a much smaller angle when put up in an airstream. However, while analyzing this result, I found out that the drag coefficient is not always...

diffusion coefficient meaning is the coefficient of particles diffuse when different in concentration. How about diffusion coefficient of a particle? the trajectory where a particle diffuse?

Hello, I understood that in low velocities the standrad drag equation: F_d=\frac{ρv^2C_dA}{2} Could linearized to something like: F_d=γv I am looking for the drag coefficient(either γ or Cd) for either a prolate or a tri-axial ellipsoid at low velocities (less than 0.5 m/s) in water. I found...

Consider the system: A block of mass M is placed on a level table and connected to a mass m by a light string running through a pulley. If mass m is released, it will start to fall and the wooden block will be pulled across the table. Prove that the kinetic friction coefficient can be given...

Hi Everyone, I'm trying to find the initial speed of a motorcycle that was involved in an accident. The driver lost control and the bike dragged along the asphalt for some distance. I know several variables but my physics is not a strong suit to say the least. Any help would be much...

β= (1/v)(∂v/∂T)constant pressure. What is the v represent? molar volume? If I am given the β and the change of temperature, how to calculate the change of volume? or it is not enough information to calculate it? Thank you.

Hi I have a question on the transmission coefficient in classical optics. When we say that a medium has a transmittance of e.g. 99%, then 99% of the incident light intensity is transmitted. But will the light also acquire a phase? I tried searching the web, but all I found was this...

Homework Statement Let X and Y be two independent exponential random variables with a common rate parameter λ>0. Let W=X-Y. a)Find the pdf of W=X-Y b) Find the coefficient of kurtosis of W=X-Y Homework Equations f(x)=λe^(-λx) f(y)=λe^(-λy) f(x,y) = (λ^2)e^(-λ(x+y)) Kurtosis =...

$$ u_y(x,\pi) = \frac{x}{\pi} + \sum_{n = 1}^{\infty}nB_n\sin xn\cosh\pi n = 0. $$ How can I solve for $A_n$ here?

Coefficient of friction!? Homework Statement How would you figure out the coefficient of sliding friction between two sheets of paper ?. Homework Equations The Attempt at a Solution I intended to make a ramp out of one paper and and put the other paper on top of the ramp. Adjust...

Ok so I tried making myself a free-body diagram but I reached a dead end.. Step 1) fkinetic = μkn fkinetic = μk(251) fkinetic / 251 = μk Step 2) Fx: T1 Fy n = (m)(g) = 251 N 120.5 N Step 3) ƩFx = m(-a) since it's moving the left or ƩFx = 0 (since it's moving at CONSTANT velocity) ƩFy = ma...

Homework Statement So a hot wheel was put on a linear track, and one end of the track is slowly lifted until the cart starts to move. The height of the one end is measured as 6.45cm and distance (or hypotenuse) is 189.5cm mass of hot wheel is 45.7 g Homework Equations PE = mgh KE =...

Homework Statement Original Length = 6.736 mm Final Length = 7.802 mm Initial Temp = 21.7 C Final Temp = 99.5 C Homework Equations Coefficient = (Change in Length) / (Original Length * Change in Temperature) The Attempt at a Solution Change in Length = 7.802 - 6.736 = 1.066 mm...

Homework Statement A 20.0g object is placed against the free end of a spring (k = 25.0 N/m) that is compressed 10cm. Once released, the object slides 1.25m across the tabletop and eventually lands 1.60m from the edge of the table on the floor. Is there friction between the object and the...

Homework Statement For our lab we had to find the coefficient of kinetic friction for a cart on a linear track. We pushed the cart on the track and it went through two photogates which measured the time it spent in the photogate. So through the 1st photogate = 0.0040s 2nd photogate = 0.0062s...

Homework Statement We have a car with mass of 1200kg driving at 55km/h. It suddenly starts breaking. The breaks "work" on every of the 4 wheels with the constant torque of 12Nm. The radius of the wheels is 0,21m. Question 1: How long does the car travel before it stops if the wheels have...

Hi all, I'm in an algebra based physics class so I apologize if the way I approach the problem is different from what you might be used to. A buddy of mine is calc based physics always gets confused about how I set the problems up. Also, this is my first post! Thanks in advance for the help...

Homework Statement (see attachment) Homework Equations The Attempt at a Solution I am not able to understand the question and build a scenario in my mind. The question asks the distance traveled when the cylinder starts slipping. I can't think of the situation when the cylinder...

Homework Statement A solid's thermal expansion coefficient is defined as δ= \left(\frac{1}{V}\frac{∂V}{∂T}\right) In the Debye model and at the low-temperature limit, show that δ is a positive quantity and is proportional to T^{3}. At the high-temperature limit, show that δ is still...

If you have the impact force on the y-axis (in Newtons) and the time on the x-axis (in milliseconds), can you get the coefficient of restitution from just this? The plot is for the force of impact exchanged between two balls as a function of time. I know the coefficient of restitution is the...