When an incandescent light bulb is switched on, it can take a few moments for the filament to fully heat up and reach its equilibrium temperature. Assume the filament of a given light bulb is made of Tungsten, and also

assume...

Final Temperature of a Lightbulb filament]]>

View attachment 197173

Source: Introduction to Engineering Thermodynamics by Sonntag/Borgnakke.

Thank you.]]>

I've determined and calculated the density, specific heat, thermal...

How to calculate heat dispersion through solid copper rod?]]>

But why is EM not non-local?

How to make EM non-local?]]>

Compute the Integral: ##\int_{-\infty}^\infty \space \frac{e^{-2ix}}{x^2+4}dx##

##\int_C \space f(z) = 2\pi i \sum \space res \space f(z)##

At first I tried...

Improper Integral Using Complex Analysis]]>

Lhc creation/destruction]]>

Advice for getting through the physics major?]]>

Are the unit cells of the strained crystal still the periodic elementary building blocks of the transformed crystal?

Does the transformed crystal own the same volume as that of the perfect crystal?

Can we treat the strained crystal as the...

Strain, crystal and all that]]>

The theoretical value is 26.3m/s Resistance forces were not accounted for in this calculated value.

To...

Manipulating the Drag Equation]]>

Reversibility of physical law]]>

As one rolls back the clock, the size of the observable universe becomes smaller than it is today.

Does this mean that all of what we observe today was more densely packed yesterday than it is...

What is meant by the size of the early observable universe?]]>

Plateau models of inflation after Planck]]>

Beware, although this starts off sweet, it turns evil...

http://www.youtube.com/watch?v=6n5OZhEnZp8&NR=1

https://www.youtube.com/watch?v=6n5OZhEnZp8&NR=1

For dog and puppy lovers]]>

1. John is traveling with an elevator upwards with the speed of 3.0m/s. She drops her bag. How big will the acceleration be right before it hits the elevator floor?

My answer is 9.82m/s^2 is that correct?

2. Assuming the bag is...

Elevator problem]]>

I have a task right now that requires me to calculate the energy savings that would be made by using a variable speed drive.

Calculating energy savings using a variable speed drive]]>

Most Likes Page]]>

I learned in the earlier chapters that peaks and valleys of a fxn have points where f'=0 (i marked them with red x). A few chapters later it said if a fxn has 2 roots, then f'=0 (still the 1st graph).

So does that mean if the graph of a fxn is like the 2nd graph,...

Do all the peaks and valleys of f have f'=0]]>

Why use Earth as a gravity assist?]]>

a) What is the magnitude of the net gravitational force on the m2=10kg mass? Assume m1=20kg and m3=15kg.

b) What is the direction...

Magnitude of net Gravitational Force]]>

I mean a general C++ source code should be...

Assembly language programming vs Other programming languages]]>

What would have happened to that particular germ, had it not infected someone?]]>

There is three things P, Q, R. The density of P is 2000 kg/m

Buoyancy: 3 solid things have a different position in the water]]>

Imagine the classic Train Paradox, except instead of lighting strikes we have an observer at the centre of the train shooting laser pulses towards the rear (Event E1)...

Confusion with relativity of simultaneity]]>

And it is also very strange that the right side O.K but left side is not but everything is the same for left and right.

A fractional latex code]]>

A 425 gram mass is attached to a horizontal spring. The spring is known to have a spring constant of 84.6 N/m. The mass is free to slide along a friction less surface.

a) The mass is then pulled to the side a distance of 5.67...

Horizontal Spring]]>

Now suppose A and B are two detectors that register polarization-entangled photons passing...

Are entanglement correlations truly random?]]>

View attachment 197158 Here is what I have so far. Am I going the right direction?

If so, how do I go about finding the total current?

See photo above.

See...

After 14ms the current drops -- Find the capacitance at C]]>

I'm trying to find the output voltage ripple of a buck converter by using just the waveforms and the inductor ripple.

I know that the answer is supposed to be D(1-D)Vin/(16*L*C*f^2) but I keep...

Alternate derivation of output capacitor ripple voltage buck]]>

I am supposed to write a program in C that does the following:

It creates a 2d array from your specifications and as inputs takes only letters 'a' to 'z', 'A' to 'Z' and '*' and nothing else. It should immediately exit if...

Help writing a program (crossword puzzle)]]>

What amazed me was the...

Wait But Why: Neuralink - Elon's new company]]>

Thanks in advance,

Kathy]]>

An antenna is modeled by a 40ohm resistor in parallel with a capacitor with Xc = -j25. The antenna is fed

by a lossless 50ohm signal line 0.15 wavelengths long. Use a Smith Chart to find the input impedance to

the transmission...

Smith Chart problem]]>

I built a multiloop circuit for a project. The 4.2v is from mini-USB. The 3.7V is a lipo battery. The circuits are A/V Transmitters (LC circuit) which have an impedance of 75 ohms. The resistor is a 470-ohm resistor. I don't...

LRC circuit help]]>

Lots of important lessons here, for scientists, teachers, and the general public who consumes and often makes personal decisions based on science news.]]>

QM Textbooks with Interpretations]]>

Delimiting your Latex code]]>

View attachment 197152 ...

A P-V diagram question]]>

300 kPa pressure and v=0.5

The state is fixed. I should find the temperature and quality if defined.

Table values for temperature

T P vf vfg...

Calculation of specific volumes]]>

View attachment 197148

View attachment 197149

Why specifically 1/2 is the coefficient in C

I understand the sum...

Integral as a sum]]>

I've gone about graphing the below equation by inserting values in for y and then solving for x:

y(x-1)=x

For instance, I say y=3 and then solve:

3(x-1)=x

3x-3=x

3x=x

3x=x

0=x

Graphing a strange equation]]>

I am trying to understand why books always point as a fact that hydrostatic force on the bottom of a open liquid filled tank doesn't depend on the force due atmospheric pressure because they these forces cancels each other....

Forces due to atmospheric pressure won't cancel in an open tank]]>

Infact during isochoric and isobaric processes $$Q_{isochoric}=n c_v \Delta T$$

$$Q_{isobaric}=n c_p \Delta T$$...

Does efficiency alway depend on reversibility of the engine?]]>

A thin walled spherical shell with a mass of 0.605 kg and a radius of 0.0402 is released, from rest, at the top of an incline. The spherical shell rolls down the incline without slipping. The spherical shell takes 7.49 s to get...

Statics and Rotational Dynamics]]>

My specific questions are as follows:

Is there a lab experimental evidence a must to...

Question about the Scientific process]]>

It has an Impact Factor of around 4, but what's the perception? Is it respected? Is it considered a good journal?

There isn't a qualitative judgment online. My boss seems to look down on it, but it has a good impact factor.]]>

The Diffraction Limited Spot Size with Perfect Focusing

View attachment 194196

...

The Diffraction Limited Spot Size with Perfect Focusing - Comments]]>

I have James Stewart's Essential Calculus Early Transcendentals...

Good textbooks for really learning calculus?]]>

A pile driver of mass 220 kg is allowed to fall from rest through a distance of 1.8m on to a 380 kg concrete pile to drive it into the ground. Each impact drives the pile into the ground by 200 mm. Assuming that the pile driver...

Pile Driver - Energy]]>

Fetal Lamb in a Baggie]]>

in a metal stamping machine, the upper die block has a mass of 35kg and falls from a height of 2m on to a fixed metal block.

if the depth of indentation is found to be 10mm, find the average stamping force assuming the upper die...

retarding impact force when object impacts stationary object]]>

is it safe to live 100 km from Fukushima for short time?]]>

The...

New Dog Breed Evolutionary Tree]]>

In the "perche i nostri discorsi" thread, selfAdjoint gave a concise sketch of the direction that Carlo Rovelli sees in loop gravity

1.its possible to change simple analog radio device (reciever) to cosmos radio waves reciever or just cosmos radio with relativy small price.

if you know how please ilustrate it with images, thank you very much.]]>

Would it be useful to make a study of the computational effectiveness of equivalent codes written with Matlab, Mathematica, R Code, Julia, Python, etc. in a set of typical computational engineering problems like...

Comparison of high-level computer programming languages]]>

I am going over problems for exam study - here is the question with my submitted solution. Anything helps, just trying to correct mistakes so I can study the problems.

Two capacitors C=3mF, C=2mF are initially discharged. They are...

Two Capacitors connected in Series and to a 10V battery.]]>

@Greg Bernhardt : Is PhysicsForums...

March For Science, April 22, 2017]]>

How to get the perfect exit of Gymnastics Bars?

In "exploration" you have to see the measurements, the angles, velocity trajectories, mathematical tools....

Mathematical topics for high school investigation]]>

Oldest galaxy to date: UDFy-38135539]]>

Importing material properties in ANSYS ACP]]>

Thanks!]]>

Bring Me A Flower

Flowers have been a very popular contest theme. We have had many glorious photos over...

PF Photo Contest - Bring Me A Flower (4/22-5/5)]]>

Motorcycle engine build plan help needed]]>

Aristotle and geocentric]]>

What does "distinct phase change" mean here? First to understand this I should...

What is a distinct phase change?]]>

Basically I am looking at the second term on the RHS in this equation

$$ d/dt \int_L dr.A = \int_L dr. \partial A / \partial t + d/dt \int_L dr.A$$

The author has a field vector A for a...

Time differentiation of fluid line integrals]]>

Object load distribution]]>

$$\int_{-\infty}^\infty \space \frac{cos(2x)}{x-3i}dx$$

$$\int_{-R}^R \space \frac{e^{2ix}}{x-3i}dx + \int_{C_R} \space \frac{e^{2iz}}{z-3i}dz = 2\pi...

Another Improper Integral Using Complex Analysis]]>

Once again thank you to anyone that will tack the time...

making life for space]]>

At this point, they probably wish that they can pay the guy 20 million dollars to make the problem go...

United Airlines is a terrible business]]>

Solve the particle in a box problem using matrix mechanics?]]>

I think we have all seen a sci-fi movie where the characters are stuck in a space where they are trapped in a sort of "warp...

Conceptial question about warping spacetime]]>

As I understand it, the difference between the quantum field theory and string theory is that in the former, physical field is considered as the fundamental reality, while in the latter it is believed that everything comes out of strings. My question is, by everything do...

What exists between Strings in String Theory?]]>

Hello!

Surprisingly I get different results when I try to compute the inverse tangent function.

My goal is to compute it both manually and using calculator in radiant mode.

My goal is to compute...

Computing arctan (inverse tan) function]]>

I've been working on a very low scale, totally elastic 2D physics engine for a while, this is only for learning, it will serve no important purpose when it's complete, I'm just building it for fun really, to keep the...

Calculating transferred spin]]>

But with...

Why do maglev trains use attraction vs repulsion]]>

I need to know a bit about lightning/discharge, in a small scale ofcourse.

I have the impression that we can somehow (with a battery) charge a metallic tip and then if we put another metallic tip close enough, a lightning will be created. Is this correct?

In addition, I would like to...

Lightning movement]]>

The figure shows a metal coil labored as A. Heading torwards a region where a uniform static magnet field exists, poiting torwards the ground (hence X). The coil moves with the same constant velocity. As it enter the magnet...

Current graph]]>

For the vector field F(r) = Ar

Volume of...

Calculate the volume integral of divergence over a sphere]]>

Control theory]]>

How is the dark hole formed?]]>

GUT Scale]]>

In our physics course, we were studying one dimensional waves in a string. There, our teacher stated that the kinetic energy in a small piece of a string is [tex]dK=\frac{1}{2}μdx\frac{\partial y}{\partial t}^2[/tex] were μ is...

Kinetic energy density in a string (derivative)]]>

Any thoughts or insights?

E.g. I liked the "... as Cassini becomes part of the planet itself ..." on 3' 12'' ...]]>