Relationship Definition and 999 Threads

Homework Statement Homework Equations Please see below. 3. The Attempt at a Solution The idea is to find Bmin. We know: $$ \tau \frac{eB}{m}\gg 1 \\ \\ \rightarrow \frac{eB}{m}\gg \tau$$ Points: [1] We are given $$\tau \propto \frac{1}{T^{2}}$$ . [2] We are also given a conversion...

##H^2(t)-8ρπG/3=-k/a^2(t)## (Lets suppose a(t)=1) then ##H^2(t)-8ρπG/3=-k## In equations ##k## can be -1,0,1. Then If ##k<0## then ##-k>0## then ##H^2(t)-8ρπG/3>0 ##→Hyperbolic Universe. This means ##Ω_k>0## I mean If ##k## negative ##Ω_k## must be positive isn't it ? I am confused...

This is not homework. I understand that cross-polarizing (using 2 polarizing filters) will reduce the transmitted light intensity "I" to ##cos^2{\theta}##. This is well understood. I have played with polarizers for years. I have a set of polarizing filters and also bought an official variable...

Hello to all, new member here, stand back! I've built a few prototype vertical axis wind turbines and have been on a major learning curve trying to find the best pma( permanent magnet alternator) to match my mill. At first the reasoning seemed simple. Find a pma and adapt the mill to drive it at...

Given the two standard definitions (1) A computable set is a set for which there is an algorithm which terminates after a finite amount of time and correctly decides whether or not a given number belongs to the set. (2) A computable number is a number which can be approximated to any degree of...

So I know that weight correlates with friction, as in more weight of an object means that it will experience more friction. However, what is not clear to me is why this occurs on a molecular level. Thanks for the help

What is the relationship between light and time ? Could light actually be time ? Sorry if its a very naive question. I will be grateful for all responses.

Homework Statement How is ##\frac{v}{v_M} = \frac{\sqrt{A^2 - x^2 }}{A}## derived? Homework Equations n/a The Attempt at a Solution I don't see a right angle in the picture anywhere, so I don't see how pythagorean's theorem is valid.

Seems exist some relationship between the inverse of a matrix with the inertia tensor, looks: This relationship really exist?

Alloys have higher resistivity than pure metals. In real life, our voltage source ,i.e. battery, is constant. Using the formula H=V^2/R, we get that resistance is inversely proportional to heat. Alloys, in that case, will produce less heat as their resitivities are low, so are their resistances.

Hi I am new here! hopefully someone is kind enough to reply fast and help. so the question I am stuck is: Describe the relationship between two sets A and B ( A and B are non-empty) if: a. Pr(A|B)=Pr(A) b. Pr(A/B)=0 c. Pr(A/B)=Pr(A)/Pr(B) (Sorry guys can't get the fraction signs working! so...

This is probably pretty basic but I've never actually seen an explanation of how exactly the sine wave relates to the physical waves it is so commonly used to represent. Could it be imagined as like the periodic thumping of a speaker where the peak of the sine graph represents maximum air...

I've always just accepted that as you scale down a mechanical system the frequency and Q factor both increase. For example, this Wikipedia page simply says that "Small bells ring at higher frequencies than large bells". But for a driven damped harmonic oscillator, what is the exact relationship...

Many physical laws involve relationships between time derivatives to space derivatives of one or more quantities. For example, thermal conduction relates the thermal energy time rate of change [dQ/dt] to temperature space rate of change [dT/dx]. In fluid flow, the Navier-Stokes Theorem relates...

I came across a question: Four bulbs with different power rating, bulb A (240V, 40W), bulb B (110V, 36W), bulb C (12V, 60W) and bulb D (6V, 0.5W) are connected to relevant power sources. Which bulb is the brightest. At first, i thought the highest power will be the brightest. But the answer is...

Hello everyone, I'm new to this forum and this is my first post so go easy! I have an engineering problem which I am uncertain as to how to solve. I am trying to design a basic ballast system for pumping seawater. The idea is to use compressed air to evacuate the water through a series of...

Homework Statement Homework EquationsThe Attempt at a Solution I could find how to solve #2,4, but I don't understand what #1,3 need to me. How can I prove some functions are scalar field or vector field?

Hello all, I have a homework question that I am almost 100% sure that I solved, so I do not believe that this post should go into the "Homework Questions" section. This thread does not have to do with the answer to that homework question anyways, but rather a curiosity about whether or not this...

Hi all, I am very confused on how to define the vector product or cross product in a physical sense. I know the vector product is a psuedovector, and that it is the area of a parallelogram geometrically. However, I know it used used to describe rotation in physics. As with torque, magnetism and...

Homework Statement One of the three types of radioactive decay is "β decay", during which protons decay into neutrons or viceversa, emitting either electrons (β) or positrons (β+) at high velocity as a result. In one experiment, a β source and β+ source are placed 10 cm apart from each other...

I just took a test today, and I want to see if I got the right answer. I sort of guessed. Here's the question: Which statement is correct? a) When Q<K, then ∆G=1 b) When Q<K, then ∆G=-∆S c) When Q=K, then ∆G=0 d) When Q>K, then ∆G=1 e) When Q>K, then ∆G=-RT I put C, because when Q=K, the...

Is there a relationship between amplitude and phase response of a realizable filter? For the purpose of ease, let us consider only a FIR digital filter. I would like to design a FIR digital filter with a given frequency response (amplitude and phase responses given as a function of frequency)...

Homework Statement Assume you are given the entity Person. This entity has 3 attributes: Name, Name of child, Name of parent. Now, assume you want to modify your design of ”People” database above to include additional information about types of people such as sex, and people who are parents...

Firstly, apologies if this is in the wrong thread. I'm currently writing a presentation on the physics of getting a spacecraft from Earth to Mars in the near future. In my research I've come up against Porkchop plots which seem to plot contours of equal characteristic energy so you can find...

let a and b be constants and let $$y_j = ax_j+b$$ for $$j = 1,2...n$$. What are the relationships between the means of y and x, and the standard deviations of y and x? I'm not sure what they are wanting here?

I am taking thermodynamics this semester as well as a course in differential geometry of surfaces, and I am seeing a lot of overlap. For example, I can create a "state space" isomorphic to R3 of TxPxV I can then define a surface on this space of PV=NkT I can define quasi static state equations...

Scaling - Inverse relationship between uncertainty and mass I’m trying to express Heisenberg's Uncertainty Principle in a simplified formula that is not boundary unlimited and still capture what I believe is an inverse relationship between uncertainty and mass - the "scaling hypothesis". I...

Homework Statement What is the relationship between a1 and a2 A.a1=a2 B.a1=2a2 C.a2=2a1 D.a1=a2√2 E.a2=a1√2 F.There is no simple relationship between the two acceleration Homework Equations a = F/m The Attempt at a Solution I am quite confused with the second pulley , so the weight of m2 is...

Homework Statement (Excerpted from a longer, multipart problem but essentially) Show that for an ideal gas, $$ \frac{\partial p}{\partial T}\bigg)_\mu = \frac{S}{V}. $$ Homework Equations • The ideal gas law, of course $$ pV = Nk_{\rm B}T $$ • Pressure, temperature, and chemical potential...

Hello, I am currently taking Organic Chemistry and was wondering what is the relationship between bond length, hybridization, and resonance? In other words, do some hybridization have smaller bond length? How is that affected by resonance?

I've tried to relate Biot-Savart's Law to Ampere's and I've found a contradiction, which I guess is due to a naive use of Ampere's. If ## \int \vec B · d\vec l = \mu_0 I_{enc} ## is applied to a circle of radius R around a current element ##Id\vec l## we have ## B·2\pi R = \mu_{0} I_{enc} ##...

I got a B.S. in Mechanical Engineering and I am now doing a PhD in Nanotechnology in which I am synthesizing a nanomaterial. Someone just told me that nanotechnology is more like mechanical engineering and materials engineering than any other thing. Based on my work I can see the relationship...

Homework Statement A 20 kg wagon is released from rest from the top of a 15 m long plane, which is angled at 30° with the horizontal. Assuming there is friction between the ramp and the wagon, how is this frictional force affected if the angle of the incline is increased? Homework Equations...

Not all DEs have a closed form solution. Some DEs have an implicit solution only - you cannot algebraically solve one variable of interest for another. I have seen on this forum people solving DEs in terms of infinite series. How does one arrive at such a solution, and can an implicit...

What is the relationship between density of energy stored in a magnetic field and the magnetic force?

I had this problem in my exam. It required me to calculate relative permittivity of a dielectric slab which acquires a surface charge density of 800micro Coulomb/m^2 when subjected to an electric field of 10^8 V/m. Applying E=sigma/(2epsilon), I got relative permittivity as 0.45 which is less...

Homework Statement Hi I need to know the derivation of the equation HT2 = delta HT1 + delta Cp delta T and I'm really unsure of where to find this. Does anyone know the derivation of this relationship? C represents the the specific heat of the substance in question. H represents enthalpy...

I have been looking everywhere for some equation that relates temperature and pressure at a constant volume for water. I am doing a project where I am designing a solar collector and it's thermodynamic processes and I want to ensure my values are accurate in a controlled volume. Attached is the...

A car of mass 1kg rests on top of a large flat mass of 1,000,000 kg (10^6 kg). They are at rest (relative to the sun) in space. The car has a battery and an electric motor with 100% efficiency. We can assume that when a torque is applied to the wheels, they roll on the surface of the flat mass...

is the hybrid orbital the solution of Schrodinger equation ? Or why we have to make orbital hybridization?

[FONT=Tahoma]I have been investigating the damping of an oscillating mass on a spring by a piece of card of varying surface area, in order to work out the damping constant λ for the equation y = A₀ e-λt sin(ωt). I took the natural log of the amplitude of each successive oscillation and plotting...

I always wondered when they say as you approach a body having sufficiently high mass time slows down considerably but is it possible that if I look at an object and that object were to move close to say a black hole as it nears the event horizon the speed of the escaping light should decrease...

A question I have, the moon drags the oceans which can in turn be used to create tidal power on earth. Does this then mean that the energy of the Universe is theoretically infinite? As there is no shortage of masses moving around other masses than can have a similar effect. Is this, strictly...

Consider the linear ODE y''-(ax-b)y=0 . Wolframalpha gives Ai(\frac{ax-b}{a^{2/3}}) and Bi(\frac{ax-b}{a^{2/3}}) as the two independent solutions where Ai(z) and Bi(z) are the Airy functions. I tried to find an answer myself, so I substituted y=f(x) e^{cx} in the equation and tried to...

Homework Statement We performed a lab to find an experimental value of gravity. I used a ramp with a height of 0.08 m, and the ramp was 1 m long. The ramp made an angel of approximately 4.59 degrees with the horizontal. We used software to calculate velocity with respect to time and position...

I recently watched a documentary presented by Professor Brian Cox called Human Universe. In it he was wondering how much leeway he would have, if he was "the creator of our universe", to alter the physical constants. He then went on to say that if he altered the speed of light one way then...

So I'm really confused with the relationship between magnetic field strength and voltage. Say you have a battery (with a DC voltage) with 4 coils, when voltage increases, does magnetic field strength increase? Is there any law (i.e. Faraday's law) that supports this?

Maybe this question is pretty simple to tackle, but I’m really confused with it. Perhaps I’m just overthinking. The question is: The glue on a piece of tape can exert forces. Can these forces be a type of simple friction? Explain, considering especially that tape can stick to vertical walls...

While I am familiar with the derivation of the relationship between mean translational kinetic energy, ##<E_k>##, and temperature, ##T##, for an ideal gas (namely ##<E_k> = \frac{3}{2}k_B T##); I fail to see how we can establish such a relationship for solids, liquids, and even real gases. Could...

The mass-radius relationship for a white dwarf star is defined by : R= (9pi)^0.66 /8 * h^2/m1 * 1/(Gm2^1.66*M^.333), where m1= electron mass, m2=proton mass, G=grav. constant, h=planck's constant I want to take a proportion with the solar mass and solar radius, which would involve a division...