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

aggression in men]]>

Limx-->positive infty arctan(1+x)/(1-x)

I just need to know if my answer is right.

Knowing that when the leading coefficients of the x when its the same, then...

Arctan limit (without hopital)]]>

How it works is it acts like a shock absorber, but within a small, one inch long by one and a half inch wide...

How can you negate impact force?]]>

I encountered this weird theory that I don't really believe to be valid. But it sounds pretty plausible, so I'm going to let you guys tell me whether it is correct or not.

Anyway, the link is here: http://www.onelife.com/evolve/degen.html (warning: possible...

Human Genome Degeneration]]>

Engineering or B.Sc.?]]>

What is Dark Matter?]]>

Find the velocity of v as a function of displacement x for a particle of mass m which starts from rest at x=0 and subject to the following force:

[tex]F=F_0+kv[/tex]

You could say mv = F0*t + kx, but the answer in the back of...

Solve the differential equation F=F0+kv]]>

Why can't sin(x^2) be expressed in terms of sin(x)?]]>

invariant:

(c) y(t) =∫

(e) y(t) = x(−t);

There are more sub-questions but I was able to...

Time Invariance]]>

Grounded conducting sphere in uniform electric field has potential

V(r,θ) = -V

Find E

In...

components of E field]]>

50th anniversary of the original Star Trek]]>

The problem is to find the current in the 25 ohm resistor (left side)

http://imgur.com/a/luKCW

KCL

KVL

ohms law (v=IR)

My attempt at the solution was...

Finding current in the 25 ohm resistor]]>

Does the incompleteness theorem apply to physics at all?]]>

Show that the Lorentz Force Law, [itex]\frac{dp^{\nu}}{d \tau} = -q U_{\mu} F^{\mu \nu}[/itex], is consistent with [itex]P^\mu P_\mu= -m^2.[/itex] Here U is the 4-velocity, F is the Electromagnetic Tensor, and p is the...

Lorentz Force Law - Tensorial Form]]>

Why the square of the wave function equals probability?]]>

Any...

Astrophysics Science Fair Project Ideas??]]>

I have been trying to solve a long problem but my answer differs from my books answer with just a few peculiar terms.

My answer:

##x_1' \vee x_0'x_1x_2 \vee x_0x_1'x_2' \vee x_2##

Book:

##x_1' \vee x_2 ##

My question is:

Is it possible to simplify ##x_0'x_1x_2 \vee...

Boolean algebra - is it possible to simplify expression to 0]]>

Is Introduction to Theory of Numbers by Hardy good ?]]>

BIG New Scientific Ideas?]]>

Are we in a simulation and quantum tunneling?]]>

Can I derive the expression for Z_PDF(z) where:

Z = t(X,Y) = X + Y

By starting with:

Z_PDF(z)*|dz| = X_PDF(x)*|dx| * Y_PDF(y)*|dy|

Z_PDF(z) = X_PDF(x) * Y_PDF(y) * |dx|*|dy|/|dz|

and then substitute the deltas with derivatives and x and y with expressions of z?]]>

Two rods of the same material, of equal length

Derive an expression for the deflection between two forces]]>

Here is the last page of part 5.

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

Discuss, discuss, discuss...

All I know is that Hillary and Trump look like the most popular at the moment.]]>

For a larger project we had to redesign a truss to prevent certain members going beyond yield stress.

I've found that due to the nature of the reaction forces and the supports used, the only way to do this is to introduce an...

How can I solve this indeterminate truss bay?]]>

CW complex and Hausdorff]]>

Find the directional derivative using ##f\left(x,y,z\right)=xy+z^2## at the point (4, 2, 1) in the direction of a vector making an angle of ##\frac{3π}{4}## with ##\nabla f(4, 2, 1)##.

Directional Derivative at an Angle with a 3d Gradient]]>

"A free neutron will decay with a half-life of about 10.3 minutes but it is stable if...

Weak force - only free neutrons decay?]]>

An atom at rest can undergo radioactive decay, ejecting an electron at a maximum speed of 0.5c. If the atom in a particle accelerator is observed to produce an electron traveling at 0.75c, at least how

fast must the atom...

Modern Physics question -- an atom ejecting a relativistic electron]]>

Should I skip honors physics?]]>

So I started to read some papers for my master thesis in environmental physics (no idea if this is the correct translation) and there they talked about "drogued" drifters and "undrogued" drifters in the ocean, from which they...

drogued drifters]]>

Additional textbook to Sakurai and Ballentine]]>

I've already taken calculus for mathematicians, linear algebra, classical mechanics, special relativity, and electromagnetism.

The topics it...

Best analytical mechanics textbook recommandation]]>

Show that any vector in a vector space V can be written as a linear combination of a basis set for that same space V.

http://linear.ups.edu/html/section-VS.html

We are suppose to use...

Math proof]]>

How can time dilation be the same for both observers?]]>

Now it seems likely that you would see a virtual image of the point source...

imaging by cylindrical concave mirror]]>

I can't understand the solution to Problem 1.4(a). The solution is the following:

View attachment 106576

What puzzles me is that

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]]>

Tweaking Latex rendering (for GitHub pages)]]>

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 two questions - the first is about an approximation of a central gravitational force on a particle (of small mass) based on special relativity, and the second is about the legitimacy of a Lagrangian I'm using to calculate the motion of a particle in the Schwarzchild metric....

Special Relativity Approximation of Gravitation]]>

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 this really cost efficient for the amount of calories/nutrients I get?

If not then what could I possibly cook or buy to save money? I would like to continue eating...

Is a Subway footlong worth the money?]]>

frequency at a certain voltage when selecting a pulse transformer.

The one I'm looking at has an ET value of 45Vusec.

I'm feeding it 22.5KHz at +/-6VAC square wave. It seems to work fine but I fear it is...

Determine minimum working frequency from the V*usec value of a pulse transformer?]]>

P = NK

Re-arrange variables in the Van Der Waals equation of state, Eq. (1), so that V always appears in the equation as V/(3Nb) and P appears as 27b2P/a. Then T should appear in the combination 27b...

Rearranging variables Van Der Waals EoS into new variables]]>

From rest, how fast would two particles be going at the instant they collide ( if they attract) or when they're infinitely far apart (if they repel)? Explain carefully.

Particle A: 3nC

Particle B: -4nC

Each has a mass of 7 mg....

Is it possible for opposite charges to repel each other?]]>

I am in the process of designing a buck converter.

This is the regulator I have chosen. http://www.aosmd.com/pdfs/datasheet/AOZ1242DI.pdf

The input will be 13V

output will be from 12 to 6 volts (will be adjusted via a thermistor on the FB voltage divider R2)

Now,...

Problem with a buck converter: my error, or the device's]]>

Interview with a Physicist: David J. Griffiths

...

Interview with a Physicist: David J. Griffiths - Comments]]>

An internally compensated op amp has a DC open-loop gain of 1,000,000 (V/V) and an ac open-loop gain of 40dB at 10kHz. Provide the expected gain in dB at 1kHz...

Please help, I don't know what to...

Predicting AC open-loop gain for an internally compensated op-amp]]>

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...

what's the inertia of cart A?]]>

Becoming a professor at a top university?]]>

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]]>

US military career change to engineering and need advice]]>

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]]>

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]]>

Figure shows a 50 Hz, high-voltage, transmission line. The relationships between the sending and receiving end voltages and currents are given by the complex ABCD equations:...

Transmission Line]]>

Limx--->positive infinity sqrt(3x^5-2x) - sqrt(3x^5-7x)

The first thing I did was rationalize. I got (5x)/ [ sqrt(3x^5-2x) + sqrt(3x^5-7x)]. Then I divided the...

Limits..what am I doing wrong ? (Without hopital)]]>

I'm nothing without my calculator...]]>

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]]>

I recently got accepted into Moscow institute of physics and technology for a masters degree and was wondering how it would be compared to different grad schools in the USA. With other factors constant (LOR, research, etc), how would this set me up for a Phd at a top university in the USA?...

Studying at MIPT]]>

Recommended textbooks based on provided topics (supplementary undergrad texts)]]>

Let E be a bounded set in [itex] R^n [/itex]

Show that E and the closure of E have the same Jordan outer measure

Jordan outer measure is defined as [itex] m^* J(E)=inf(m(b)) [/itex]

where [itex] B...

Show that E and the closure of E have the same Jordan outer measure]]>

I'm trying to study reflection on the rear side of an optical device. I wrote a transfer-matrix code in matlab to compute the reflectance. I checked my code by comparing some basic cases with other kind of optical simulations (FTDT with Lumerical). When the incident medium is Air...

Strange results with transfer matrix (Optics)]]>

Formula For Calculating Output Power of a Turbine]]>

Code (Text):

Dec 31, 2015 Close 17425.03

Jan 20, 2016 Open 15,989.45

Low 15,450.56

Close 15,766.74 Down 249.28(1.56%)

Jan 20, 2016 Open 15,989.45

Low 15,450.56

Close 15,766.74 Down 249.28(1.56%)

What's going on with the US/Global economies?]]>

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]]>

Assume that the pressure p and the specific volume v of the atmosphere are related according to the equation ## pv^{1.4} =2.3*10^3 ## where p is in ## N/m^2 ## and v is in ##m^3/kg ##. The acceleration due to gravity is...

Depth required for a given pressure]]>

The typical and the exceptional in physics]]>

Find the limit

$$\lim_{x\to-\infty} \frac{\sqrt{9x^6 - x}}{x^3 + 9}$$

N/A

To solve this, I start off by dividing everything by ##x^3##:

Numerator becomes...

Finding the limit of a quotient as x goes to minus infinity]]>

Match the parametric equations with the graphs.

In this case, I am stuck on this equation:

x = cos t

y = sin t

z = 1/(1+t^2)

So far I have:

x^2 + y^2 = cos ^2...

Confused with Space Curves]]>

examine the following circuit and complete the table]]>

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]]>

For instance, suppose that one wants to discuss number theory or discrete mathematics. Is this supposed to belong to

Incomplete math classification on this forum]]>

Is there any way to derive the time dilation formula?]]>

Flying cars/The Car of Tomorrow...Cheap Energy...Unlimited Free/Leisure Time...Space Travel...Robots...Computers thats do everything for us

]]>

[itex]

ax^2+2hxy+by^2+2gx+2fy+c=0

[/itex]

I am told that, if P(p, q) is a point on this conic, then the polar of P(p, q) to this conic is

[itex]

apx+h(py+qx)+bgy+g(p+x)+f(q+y)+c=0

[/itex]

How is this derived?]]>

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]]>

##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]]>

A positive point charge [itex]Q_1[/itex] (4.0 µC) and a negative point charge [itex]Q_2[/itex] are placed near each other. When a negative charge [itex]Q[/itex] is placed in the middle between the two point charges, the...

Coulomb resultant forces]]>

Lead has a mass of 11.35

mass and atoms]]>

The UK now a one party state?]]>

sam makes a punch hole with the perforater( two holes ). She presses the lever at A down with a force of 40 N. Calculate the total force which a single pin presses on the paper.

moments and force -- Forces on a cantilever hole punch]]>

I know its early for me to ask as I only began my degree, I am currently studying electrical engineering and computer science..but I've realised I would like to go study mathematics.

Can I do a masters in mathematics ? would I have to take extra classes or will I be rejected?

Or do I...

Can I do a masters in math or..?]]>

Ref: Safe Site Request:Anaconda and Virtual Box, Please]]>

Also, another quick question, somewhat related, any knowledge on how many "cascades" of different proteins making a conformational change on different new proteins can there...

How many times does an average protein fold?]]>

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]]>

|i><i|

I know the i's are unit vectors, and I know <i|i> is the dot product, but what operation is the ket-bra?]]>