Examine the behavior of ##f (x,y)= \frac{x^4y^4}{(x^2 + y^4)^3}## as (x,y) approaches (0,0) along various straight lines. From your observations, what might you conjecture ##\lim_{(x,y) \rightarrow (0,0)} f(x,y)## to be? Next,...

Does ##\lim_{(x,y) \rightarrow (0,0)} f(x,y)## exist?]]>

I'm trying to calculate a torque needed to tighten a threaded terminal. (Both male and female parts are copper alloy)

I'm using Motosh's equation which requires me to use the coefficient of friction.

Web sources tells me that the copper-copper coefficient of friction is 1.0.

The...

Static coefficient of friction between copper or brass]]>

Public Address System Prank]]>

An electric dipole field (two opposite point charges separated by some distance) has fields lines from the positive to the negative charge, but also field lines reaching to and coming from infinity. Starting from the positive charge, is there a way to compute the opening angle of the cone...

Dipole: Which field lines go to infinity?]]>

Use Bernoulli’s equation to calculate how fast the water emerges from the open tap (at position 2) in the figure(a). You may assume that the water at position 1 moves negligibly slowly

(b) The tap is rotated to create a...

Bernoulli's equation and water exit speed from tank opening]]>

A spaceship is approaching earth from the far side of the sun. The earth and sun are 8 light minutes apart and the ship is traveling at .8c. Two events are indisputable. 1) the ship is at the sun 2) the ship is at the earth....

Lorentz Transformation, Time Dilation, Length Contraction]]>

If one of the photon had eyes to see what will 'he ' measures the velocity of the other photon which is moving with 'him'? Won't it be zero???!]]>

Is aggression just part of what we are, can we...

aggression in men]]>

Proof that if the slopes of two lines a1, a2 (that are not vertical), m1,m2 satisfy:

m1*m2 = -1, then the lines are perpendicular.

I tried to use the tan...

slopes product = -1 <===> lines perpendicular]]>

"A spacecraft approaches a neutron star of radius 10 km and mass 1.5 times mass of...

what is orientation of a needle shaped spacecraft?]]>

If two particles were allowed to move freely, how fast would they be going at the instant they collide or when they're infinitely far apart? Explain Carefully.

There are no initial velocities given. The charges are -4 nC and 3...

Finding the velocity of two charges]]>

I didn't.

This was four months ago. The past three weeks my IPAD has been operating very slowly and can't seem to play media very well (either doesn't load or takes...

Never Changed My Router Password - Got Attacked?]]>

I'm using cppdroid and wrote a c code running a window on x11 (originally Ubuntu Linux) and installed a xserver on android. How could i compile this code on Android knowing it lacks the x11 headers ? Thanks.]]>

It appears that Stuart Prager is “stepping down” as director of PPPL. I wish him well.

But in the announcement it refers to a...

Tokamak News and Queries]]>

I had a lab where we had to create esters. One of the discussion questions are

What must be done before the esters are used as you suggest in (e)?

I suggested...

Making Esters]]>

The equation for inductance is then:

L = 2 X 10

Why does inductance increase with increase in distance between conductors? When the spacing is...

In power transmission why inductance L increases with increased spacing]]>

I want to derive the Friedmann equations from Einstein Field Equations. However, I have a problem that stems from the energy-momentum tensor. I am also trying to keep track of ## c^2 ## terms.

FRW Metric:

$$ ds^2= -c^2dt^2 + a^2(t) \left( {\frac{dr^2}{1-kr^2} + r^2 d\theta^2 + r^2...

Energy-momentum tensor and Friedmann Equations]]>

I'm trying to find the electric field at the origin <0, 0, 0> due to a quarter of a ring with +Q charges on it. The quarter of the ring lies on the +y-axis. Due to symmetry, the x-components of the electric field will cancel...

Finding the Electric field at the Origin]]>

##I_0 = [\frac{-R_2\omega^2C_1C_2 + [C_1+C_2]R_1R_2\omega^3C_1C_2 - R_1\omega^2[C_1+C_2]^2...

Optimization Problem with an RC BP filter]]>

I am looking for the names of the top 30 schools in North America for research work in string theory and quantum gravity.

Any feedback will be very helpful.]]>

SpaceX Needs Us!]]>

A child is at a playground, and chooses to try the spinning disc (see figure). The radius of the disc is 2.00 m, and the coefficient of static friction between child-surface and disc-surface is μs = 0.350.

In the following...

Rotational motion: playground spinning disk problem]]>

There is a grasshopper who wants to cross a log(cylindrical) of radius $$R$$.Calculate the minimum velocity required by grasshopper to just scrape the log.

First of all I have a doubt.So equations...

Minimum velocity required by grasshopper]]>

It is not some homework, so I think it is better to post here. I would like to know if my method is correct for the work of the walls x and y.

I suppose no mass, no friction and the gas keeps its temperature constant.

An external device modify the shape of a triangle but it keeps...

Method to calculate work while moving two walls]]>

My calc class is having me review precalc(which i'm really rusty on...)

21. Find sin θ, sec θ, and cot θ if tan θ = 27

22. Find sin θ, cos θ, and sec θ if cot θ = 4.

23. Find cos 2θ if sin θ = 15

24. Find sin 2θ and cos 2θ if...

Trig identities(I think?) for precalc review]]>

I will be spending 1 year in jail for selling weed (please don't judge). I am very business savvy, and have always been very good with the math I needed to know (which was mostly just algebra). I have always been interested in learning advanced mathematics and chemistry/physics,...

Teaching myself math in jail?]]>

sphere to donut mathematically]]>

Will This Put/Call Game Work?]]>

Can we use better telescopes of this type (ground based gamma rays telescopes) to image the surface and subsurface of a planet with a lot of resolution?]]>

All acknowledgements to authors of course.]]>

Some underwater fish use a jet to move forward. The body expands with water and contracts, expelling water and thus propelling forward. For these purposes, assume that a submerged fish experiences a friction drag proportional...

Squid swimming in water fluids problem]]>

A rocket sled moves along a horizontal plane, and is retarded by a friction force ##f_{friction} = \mu W##, where ##\mu## is the kinetic friction constant and ##W## is the weight of the sled.

The sled's initial mass is ##M_0##,...

Rocket sled]]>

My current question, I hope, can be more of a discussion than just a simple question and answer. Since I am into the design of all aspects of boat and sails. I have a question about...

Form Drag on Sailboat Hull]]>

The stomach bug lasts for 5 days and it is an unknown pathogen(Possibly a super version of salmonella since he...

Paralyzed by pain, possible?]]>

A 747 Jumbo Jet must reach a speed of 290km/h by the end of the runway to lift off. The 15L-33R runway at Toronto International Airport is 2,770 meters long. The main Toronto Island Airport runway 08-26 is 1216 meters long....

Simple constant acceleration/equation of motion question]]>

What does the ladder mean, though? Clearly, even if a communist country, people have their own...

How Does a Communist Economy Work?]]>

Here is a picture of the problem

For those who don't want to click the link, basically the problem wants me to calculate the surface brightness of a flat...

Surface Brightness at any angle]]>

A one-dimensional stream of particles of mass ##m## with density ##\lambda## particles per unit length, moving with speed ##v##, reflects back from a surface, leaving with a different speed ##v'##, as shown. Find the force on...

Reflected particle stream]]>

Given: A large pressurized container with a small hole in a side. The sides of the container are VERY thin such that the thickness of the sides can be ignored. The pressure difference between the container and the environment is not large enough to result in choked flow. The outflow...

Exit velocity of a gas through a hole]]>

v = rω

m

m

Does this make sense?]]>

New Member]]>

im trying to design a printed (microstrip) dipole.

Im currently having a hard time finding some good information on how to design such a printed dipole antenna.

I would really appreciate some help/hints in form of links/books/equations that can help me to design such an antenna element....

design help printed (crossed)-dipole]]>

A 1-kg standard cart collides with a cart A of unknown inertia. Both carts appear to be rolling with significant wheel friction because their velocities change with time...

what is the inertia of cart A?]]>

View attachment 106419

1) Which mass accelerates faster than g

2) What's m

3) In which condition m

Masses and combined pulleys]]>

Our Beautiful Universe]]>

It is in Warwickshire England

It moves in the wind

A box one keeps valuables...

All around the world]]>

Determine the smallest force P that will cause the spool to have impending motion.

View attachment 106527

Equations of equilibrium, and static frictional equations.

##ΣFx = 0;##

##ΣFy = 0;##...

Identifying forces in a friction problem]]>

Why is ethanol a bad choice for recrystallization of phthalic acid?

2. The attempt at a solution

I know phthalic acid is very soluble in water, so water is a great candidate to recrystallize phthalic acid. I also know...

Organic Chemistry Recrystallization]]>

Is it beneficial to get MBA beside an engineering degree in terms of enhancing my chances in getting a job?

Thanks]]>

graph of rotation curve of a cluster (not a galaxy)]]>

How would dark matter aggregate?]]>

Using experimental data, I am trying to solve the following equation for ##T_2##

$$M(t)=M_0 e^{-t/T_2}. \tag{1}$$

Here ##M_0## denotes the initial value. There were 8 data points collected for ##t## and ##M(t).## Here is the...

Solving exponential equation (using a graph)]]>

Any speculations as to what they will announce? I was thinking plumes like on Enceladus but then I realised they've already been seen on Europa. So my...

NASA Europa announcement]]>

1. Is that usually true, and...

Are green lasers Left Circularly Polarized Light?]]>

The work done by a constant force of magnitude

{\displaystyle...

Physics Maths Question Work]]>

I had a discussion with my professor. He tried to convince me but I couldn't understand the idea.

The Stokes Theorem (Curl Theorem) is the following:

My professor says that the value of the...

Why is Stoke's theorem of a closed path equal to zero?]]>

(a) Find the directional derivative of

(b) Find the directional derivative of

Directional Derivative at an Angle from the Gradient]]>

Thanks in advance.]]>

Canonical perturbation for infinite chain]]>

Searching online (e.g. Amazon) I did find some options but the reviews are usually mixed regarding precision (users will say that scales with milligram precision specs are not that...

Advice on milligram/centigram precision scale]]>

examine the following circuit and complete the table]]>

Spectral Standard Model and String Compactifications...

Spectral Standard Model and String Compactifications - Comments]]>

Two capacitors, one that has a capacitance of 4 μF and one that has a capacitance of 12 μF are connected in parallel. The parallel combination is then connected across the terminals of a 12 V battery. Next, they are...

Two capacitors in parallel: potential difference/energy]]>

http://www.dailymail.co.uk/sciencet...old-solved--strange-behaviour-atom-bonds.html]]>

If ##AA^T=A^TA##, then prove that ##A## and ##A^T## have the same eigenvectors.

##Ax=\lambda x##

##A^TAx=\lambda A^Tx##

##AA^Tx=\lambda A^Tx##

##A(A^Tx)=\lambda...

Problem about an Eigenvector]]>

If you live in a rural community with your own water system or your water supply comes in on plastic this sort of thing seems...

Losing neutral in the utility system.]]>

Electric Longboard Gear Ratio]]>

Formula For Calculating Output Power of a Turbine]]>

I am doing a problem of compression work. in order to solve it, I have to find an equation for the line and integrate it to get the work. But I don't understand why ##k = \frac{P_i}{V_i}##

P=kV...

problem of compression]]>

The vx(t) curves for two carts, A and B, that collide on a low-friction track are shown below:

What is the ratio of their inertias?...

ratios of inertia]]>

I'm a bit of a food geek and a DIY nut and I'm looking to build my own vacuum sealer for as cheap as possible. My question to you guys, is what is the cheapest material I can use that will still withstand the pressure as well as maintain the airtight seal needed? I am looking to get a...

Vacuum chambers]]>

I have encountered a problem at the university in which there is a thermally isolated container of constant volume in which the number of particles and temperature change with time(the temperature increases). The change in particle number ensures...

Heat capacity under constant pressure or volume question]]>

A little bit about myself- Non-traditional student in school for the second time. Majoring in electrical engineering. Did 4 years in the USN, got...

Hey all- New member here]]>

View attachment 106540

Hello, this problem is cracking my mind for days, and I haven't solved it yet :(

Crane dimensions: See image

Mass of the crane: 10Tons

Mass center: G

Maximum Load: 4Tons

Counterweight: P

Weight of...

Tower Crane Forces]]>

Have...

Tea, coffee and your favourite cups]]>

I can assume that in the very early Universe, matter was grouped in these areas, that matter interacted thus resulting in the formation of stars. Then, the...

Why are stars grouped in galaxies?]]>

Show that the largest possible change in the kinetic energy , ##\Delta E_{kin}##, of a particle of mass ##m## running into another particle of mass ##M## at rest in the lab coordinate system is

[tex]\Delta E_{kin} =...

Maximum change in the kinetic energy of a particle]]>

https://www.sciencedaily.com/videos/0233de5148b63e6e2bd95b0fcb0daca8.htm]]>

A 1-kg standard cart collides with a cart A of unknown inertia. Both carts appear to be rolling with significant wheel friction because their velocities change with time as shown graph...

whats the inertia of cart A?]]>

How can I see that in the frequency space the excitations are uncoupled .

I also don’t understand equation 2.50]]>

I recently started my first physics course and anticipate having lots of questions and little help from teachers, so I'm really glad to have found this.

Thanks!]]>

The typical and the exceptional in physics]]>

http://edition.cnn.com/2016/09/17/us/new-york-explosion/]]>

I need to find a rework station to desolder and solder IC with power pad under the IC. What I mean is IC with a metal contact at the bottom that you solder onto the ground plane on the pcb for better heat conduction.

Thanks]]>

Find Req in the given circuit

View attachment 106537

Series: req = r1+r2...

parallel: 1/req = 1/r1 + 1/r2 ...

Without redrawing the circuit I do:

12||60 =...

Solve for Req with T to Delta Transform]]>

Find the maximum compression in the spring, if the lower block is shifted to rightwards with acceleration of '##a##'. All the surfaces are smooth.

View attachment 106478

$$\vec{F}=m\vec{a}$$...

Maximum compression in the spring]]>

total heat flow question]]>

Here's my questions...

"This question is about electromagnetic waves...

Finding frequencies and wavelengths]]>

The one instance I have come across...

Sample preparation of powders for trace metal analysis]]>