Why colonize Mars and not the Moon?]]>

I was...

Does mass increase as velocity increases?]]>

Space station artificial gravity - how to spin up to speed?]]>

〖 mod note: click on thumbprint image to see legible image 〗

I was wondering if anyone could provide some more insight as to how to find the current through Rc. The first picture...

Transfer function question op amp + voltage divider]]>

Stupid singularity tricks.]]>

Actually E= m’c2 =gmc2, where g=1/sq rt{(1/[1-(v2/c2)]}....

massless photon]]>

View attachment 111886

Say that two charges are held a certain distance apart and are let go. Well, we see that the field lines of one charge repels the other.

And I noticed that the field lines for an accelerating charge also bends....

Do charges accelerate because their field lines are changed?]]>

https://www.washingtonpost.com/loca...4def62-dfdf-11e6-acdf-14da832ae861_story.html

I must...

Women's March around the world]]>

I'm studying electroweak spontaneous symmetry breaking at that time, see for instance Chang and Li's book ch 11. Have any one an idea that if the charge operator is defined by:

## Q = \int (- e^\dagger e + \frac{2}{3} u^\dagger u - \frac{1}{3} d^\dagger d ) d^3 x ,##

and the isospin...

Unbroken electromagnetic symmetry]]>

The movie wanted defies physic.]]>

What is the final temperature in a squeezed hot pack that contains 23.9 g of LiCl dissolved in 107 mL of water? Assume a specific heat of 4.18 J/(g⋅∘C) for the solution, an initial temperature of 25.0 ∘C, and no heat transfer...

Heat and Energy Problem Help]]>

What's your opinion of a Math without Reals?]]>

1st heat/electrical losses in motor.

2nd Friction of the water in pipes.

3rd noise.

But I'm torn between the first 2 ? Tho]]>

Usually, the discoveries on Physics, Engineering, Chemestry and Biology are...

Real advances on CS?]]>

Original wheels weighed 29 lbs

front wheels 20" x 10"

rear wheels 20" x 11"

New wheels weigh 22 lbs

front wheels 19" x 10"

rear wheels 19" x 11"

for the purposes of the exercise I will assume tire weights are the same since the...

Unsprung Weight Reduction...]]>

Torque to roll up mats]]>

I need to calculate radiation power of ball in range 400nm-800nm.

T=10000K

d=1um.

I think I need to use Planck equation and integrate that.

My equation in link: http://imgur.com/XbAUwJ8...

Energy of black body]]>

I would like some thoughts on the following quote I read from a book on the history of QM:

What 'Collapses' the Wavefunction of the Universe?]]>

By Wien bridge oscillator (abbreviated as WBO below) I refer to this circuit where

Does Wien bridge oscillator has a closed-loop gain?]]>

Find the number of distinct three letter words obtainable from the letters A,B,C,D,E in which E may occur 0, 1 or 2 times but the rest may occur only once.

Number of combinations when picking r...

Permutations with possibly repeating letters]]>

Normal liquid pumps

Metering pumps

peristaltic pumps

Liquid respiration pumps

Centrifugal blood pumps

The latter two provide pulsed flow, but I'm struggling to find a pump that can deliver both...

Would turning a pump on and off repeatedly damage it?]]>

Need Help on Drones]]>

I majored in Physics with a solid GPA as an undergrad and then I joined the Navy as an officer and spent all of my time in Special Operations with significant combat leadership experience. During my time in I also earned a masters in Physics from the Naval Postgraduate School where I...

Special Operations Officer transitioning out.]]>

Find the voltage V

Given: i

Link to circuit: https://session.masteringengineering.com/problemAsset/1824621/4/pr_2-32.jpg

V = IR...

How to find a current is this specific circuit]]>

A golf ball is struck at ground level. The speed of the golf ball as a function of the time is shown in the figure, where t = 0 at the instant the ball is struck. The scaling on the vertical axis is set by va= 16 m/s...

X and Y components of a vector using a graph of speed/time]]>

I am trying to figure out how to calculate the torque on a cam shaft.

Say we are looking at this cam and cam follower:...

[Cam Design] Calculation of torque required by cam shaft]]>

Am i being delusional in thinking ill get acceptwd,? Ive met gead students before and i dont think...

Am i ready for grad school?]]>

My understanding is that a two-quantum state system is simply a system that can only be in two states. That is equivalent to say that the observable of interest that is being considered can only have possible values. Is that the case?

If so, a classical bit can have two values...

Two quantum states and qubits...]]>

So if electrons are fired one at a time, what makes an electron go on a certain path. Say it goes on some weird path that would have implied that a force exist when viewed...

MWI and path of single electron]]>

I am practicing problems like this:

View attachment 111918

where Vs=10V, R=2kohm, they say it is like a battery + ideal diode with VD=0.7V

I have to sketch the transfer characteristic Vo=f(Vs) and draw the waveform of...

Diodes & rectifiers]]>

"A well-insulated bucket of negligible heat capacity contains 120 g of ice at 0°C. If 20 g of steam at 100°C is injected into the bucket, what is the final equilibrium temperature of the system?"

Equilibrium temperature of some ice and steam]]>

Early Quantum Entanglement Experiments basic question?]]>

It has a flowrate in and out in kg/s. Surely I should look up the enthalpy values and just mutiply with the flow rate to get power in kW.

However I know that if I convert flowrate to m3/s by dividing 1000 and multiplying by the...

Power of a pump]]>

Many worlds interpretation incompatible with quantum gravity]]>

Please start off with "Today I learned". Keep commentary to a minimum and just LIKE posts. I'll start!

Today I learned that you clean...

Today I learned]]>

I need to know what is the best type of susension system for bicycles.And also rating of a motor to drive a 5 kg load.I am still studying B E .Please it is urgent. Thaks for helping.]]>

(1) First I carry the feedback into the parallel line.

(2) I add +1/G

A block diagram reduction [sign error]]]>

Some math guy in another thread (I think it was "How smart is Tony Stark?") was complaining that mathematicians are usually...

"Hidden Figures" - enjoyable "true story" movie about sane mathematicians]]>

I am wondering whether tattoos affect chances of jobs getting a phd, that sort of thing?

I'm talking about more subtle small ones, i.e. rather than on top of the hand /fingers, on the under-side of fingers, or side of little finger or thumb

I know the obvious answer is get them somewhere...

small hand tattoos and careers]]>

A charged rod of length L=7.10 m lies centered on the

What is the x component of the electric field at a point on...

Electric Field at the End of a Line of Charge]]>

y''-16y=2e^4x. Find general solution

I have the homogenous equation which is c1e^-4x+c2e^4x, but I'm trying to find the particular solution for 2e^4x. I did...

Please help with this Differential equation problem]]>

What are other common expressions for "moving a pickoff point" which can be used as" moving a pickoff point behind of a block" or as "moving a pickoff point ahead of block."

Source:Self-made

Thank you.]]>

I took physics 1 & 2 at a community college that is very heavily focused on their engineering program. Because of this, I only learned things in physics 1...

Can I catch up on physics 1 & 2 in 3 months?]]>

I would appreciate resource recommendations preferably or an outline of approaches as to how one can compute the period matrix of [itex]X[/itex], or more...

Period matrix of the Jacobian variety of a curve]]>

Determine the inverse Laplace transform

3s+9/(s+3)^2+7

Converted to 3s+9/s^2+6s+16 to try and use the partial fractions method but getting nowhere.

I'm Not sure...

Inverse Laplace transform]]>

Ideal Undergrad Preparation for Biophysics Ph.D.]]>

Varying electromagnetic field]]>

A plane flies 413 km east from city

Vectors: Displacement, average velocity & speed]]>

Here is the last page of part 5.

https://www.physicsforums.com/threads/random-thoughts-part-5.851969/page-134]]>

There's a video on the subject here.

On a...

About the SpaceX Interplanetary Transport System]]>

The formula for centripetal acceleration (Ac) is $$Ac = \frac {4π^2r} {T^2},$$ where r = radius and T = period of rotation

The above formula can be rearranged as follows: $$Ac = \frac {2π} {T} ×...

Why does the Sin of 0.036 degrees approximately equal 2 pi?]]>

Use the given graph (see attachment) of [itex]f(x) = x^2[/itex] to find a number

if: [itex]|x-1|<δ[/itex] then: [itex]|x^2-1|<\dfrac{1}{2}[/itex].

(Round your answer down to three decimal places.)...

Use the Given Graph to find δ]]>

For this contest, you are to submit TWO separate photos. Both photos must be of the same subject or scene, but one zoomed in while the other zoomed out.

1. Any digital photo or digitally-scanned photo...

PF Photo Contest - Zoom In, Zoom Out (1/21-1/27)]]>

Determine the inverse Laplace transform

3s+9.

(s+3)^2+7

Hi iam new to the forum and still unsure how to make the equations the correct format so...

inverse Laplace transform]]>

please see attached, I am stuck on the second inequality.

attached

I have no idea where the ##2/\pi## has come from, I'm guessing it is a bound on ##sin...

Inequality quick question context cauchy fresnel integral]]>

Hi

How do I go about showing ##0 \leq \frac{2x}{\pi} \leq sin x ##?

for ## 0 \leq x \leq \pi /2 ##

I am completely stuck where to start.

Many thanks.

(I...

sin inequality proof , ##0 \leq 2x/\pi \leq sin x##]]>

Now I don't have a science backgroud

And I have a agrochemical related questions so in what forum should I look and ask?

Have a great day everyone...]]>

Today however the molding comes in a flat section. It...

carpenter's math problem]]>

Building a PC, give me your thoughts]]>

For me, it's the stupid trig functions. I can't just put angles and numbers on a triangle and solve anything. I have to tell myself "SOH CAH TOA." Every damn...

What menial mental task do you struggle with?]]>

As far as I know, once upon a time there was the Lorentz Ether Theory. This theory admitted existence of so-called Ether as a certain preferred frame, which was undetectable because of physical contraction of moving material bodies in direction of their motion.

In...

Why Special Relativity have overcome Ether Theory?]]>

masters in Statistics vs in data science? Is DS just buzz?]]>

Same as title.

Taylor expansion.

Okay - what?! I don't even know where to begin. I taylor expanded the function and pretended like n was just some number and...

Taylor expand (1+z)^n where |z | < 1 and n is any complex #]]>

What is Squeezed Light, what useful applications is it being investigated for, and how does it provide this extra...

Squeezed Light & NonLinear Optics]]>

An equation of motion for a pendulum:

(-g/L)sinΦ = Φ(double dot)

L = length

g = gravity

ω = angular velocity

Φ

The solution is...

question on general solution to harmonic EoM]]>

I would like to pose the opposite question: what does the American educational system (K-12)...

What does the American educational system (K-12) teach well?]]>

Calculating entropy for a simple scenario]]>

Do you know some book of this...

Good exercises book for relativistic electrodynamics]]>

So my problem:

- Stress = tension...

What's the difference between mental and physical stress?]]>

Each require temperature. Most required Atmospheric Pressure. Some require dewpoint, relative humidity, elevation and/or altitude.

Which calculator would...

Air Density Calculation]]>

I've looked at numerous sources of energy production and have come to the conclusion that instead of...

Whatever happened to geothermal energy production?]]>

I am wondering if the eigenstates of Hermitian operators, which represent possible wavefunctions representing the system, are always stationary wavefunctions, i.e. the deriving probability distribution function is always time invariant. I would think so since these eigenstates...

Are Eigenstates of operators always stationary states?]]>

Just a really quick question on definition of discrete subgroup.

This is for an elliptic functions course, I have not done any courses on topology nor is it needed, and most of the stuff I can see online refer to topology alot, so I thought I'd ask here.

I need it in the complex plane...

Definition of discrete Subgroup quick q]]>

1. The problem statement, all variables and given/known data

I am trying to simulate a mechanical system from a differential equations in simulink, but I don't know If I am doing it right.

I've made the model...

System of differential equations in MATlab simulink]]>

2)A solution of an acid having the formula H3NSO3 is prepared by dissolving 9,7g in water and making up the solution to...

Guys i need help in some chemistry mole exercises please]]>

A spaceship orbits Earth at 300,000 km distance at speed 0.5c broadcasting live images of the clock aboard, will the clocks difference will be 1 sec?

The orbit is a perfect circle.

Its moving close to the speed of light but stays at the same...

Near-light speed and time]]>

1. The problem statement, all variables and given/known data

In case of asymptotic notations we use the formula:

t = c * n

I dont know what is t and what is n? Is n same thing as the size of problem i.e. input data (or the data we have to process). Does t mean running time? why are...

What t & n in asypmtotic equation]]>

in several vehicles, I measured the engine torque and speed and the engaged gear while it was driven for around 100km/h. I computed the average engine speed and torque of all the times the vehicle was run with each gear and also I computed the relative frequency of the gear used. So for...

Correlation coefficient among trends]]>

If I want to make the DE dimensionless then I let ##~t = \frac{1}{H_o} \tilde t~## and...

Rescaling the equation of motion of inflation]]>

I’ve been trying to derive Posseuille’s Law and I’m very close. However there seems to be a small difference between my concluded formula and the real one but I don’t know why.

Here’s what I get:

Picture a cilindrical tube with a radius ##R## in which a fluid is flowing. From what I...

Deriving Posseuille's Law]]>

I am working on a project in astrophysics in which I need to include now some type of particle distribution (as a function of the radius).

I was wondering if there is some accepted function that would describe the number of particles per radius in astrophysics. Saturn's rings...

Particle distribution as a function of radius in astrophysics]]>

where ##\phi## is the inflaton, ##H## is the Hubble parameter, and ##V,_\phi## is the derivative of the potential with respect to ##\phi##.

To solve this...

Initial value of the inflation's equation of motion]]>

When I connect just the multimeter (as shown in the diagram) to the power source by inserting the lead into the mA connection and change the setting to read the current on the multimeter, it reads 0.

When I change the lead...

Using a multimeter as an ammeter]]>

A spaceship traveling close to the speed of light sending some data...]]>

Can someone explain why for the first derivative 3 point forward difference formula is 4f(x-h) - f(x-2h) ??

Why it's not f(x-h) - f(x-2h) ?

Is there...

first derivative 3 point forward difference formula]]>

1. ZapperZ

...

VOTE PF Photo Contest - Nighttime]]>

So I added up...

Physics 221 Calc-based question for homework]]>

Simple Geometry, Deep Math

...

Simple Geometry, Deep Math - Comments]]>

Ok, so I’ve been searching about this for a while and there seems to be a difference in explanations that confuses me. What concerns me is the exact detailed physical mechanism that makes particles cause a scatter of a photon and an emission of a photon.

The Wiki page about scattering...

Difference between Scattering and Emission of Photons]]>

Average Coefficient of Kinetic Friction between Ice and Puck]]>

How to Salvage my Academic Career?]]>

The object ,lets call it A,Its initally rest relative to us so it can be our inertial referance...

1N Force and going near the speed of light?]]>

I read in Cheng and Li's book "Gauge theory of elementary particle physics" Ch 11, specifically : Eq. (11.46) that the hypercharge commutes with the SU(2) generators, i.e.,

##[Q-T_3,T_i]=0##, I'd like to understand what that mean and how this could be proved ?]]>