Specific Definition and 1000 Threads

Homework Statement For a phasor V(x) = 8 + 4j find the sinusoidal signal that it represents if the frequency is 50 Hz? Homework Equations The Attempt at a Solution sqrt(64+16)=8.944sin(50t) so clearly this is not correct?

Hello, So I was reading up on Specific gravity, and after seeing that the reference substance is usually water, the specific gravity has the same numerical value as the density of a given liquid. Why do scientists and engineers bother to use specific gravity, what insight does it give that...

Hello, i have recently started doing AS level physics and i don't understand specific charge. My textbook stated ' An ion of Magnesium isotope (24 nucleon number, 12 proton number) has a charge of +3.2 x 10(to the power of negative 19) Coulombs. The charge of a proton is : 1.60 x 10(to the...

The portion highlighted in the paint document, is the only the specific heat for ice at -10 deg celc? What is the specific heat of ice in the interval of [-273.15,-10) and (10,0] (In deg celc) ??

A spark does not cause injury when it strikes the skin of a child. If you touch the burning stem, it can cause severe burn on your fingers? WHY? What's the difference between specific heat capacity and heat capacity?

How does the amount of heat absorbed by a body depend on the mass of the body and surrounding conditions such as pressure?

Hi everyone, I'm trying to find a function of single variable f(x) with the following properties: -It is symmetric around zero -It is differentiable everywhere -f'(x)≥0 for all x>0 -f'(x)=0 when x=0 -f'(x)≤0 for all x<0 (I think these last two actually follow from the first three?)...

I hope this makes my question clear... suppose we have a triple integral of dzdydx for [0<x<1 , sqt(x)<y<1 , 0<z<1-y] and from the sketch we can see that 0<y<1 and 0<z<1... my question is this, if we change the integration to dzdxdy we get [0<x<y^2 , 0<y<1 , 0<z<1-y], is that the only way? or...

I may have poorly titled this post, since the lecture I'm talking about isn't just about tachyons, really. What I'm referring to is what Leonard Susskind says between the 50-60 minute mark: http://www.youtube.com/watch?v=gCyImLu0HSI&feature=youtu.be&t=46m30s In the video, Susskind...

So i love astronomy, physics, maths and cosmology. I want to bring this all together so i found a degree 'AstroPhysics", and it is something which i can do well in and enjoy. I'm wounding if i should go for this degree or go for an Advanced Science Degree major in Physics? So it is more of a...

I know that if the specific gravity is less than 1, it will float and if it is greater than 1 it will sink. Now here's the question, if the specific gravity is equal to 1, what will happen? Please I need your explanations. Thank you so much!

Hi folks, I'm looking for a dye that absorbs strongly around the 490nm range. Sort of a red/orange I guess. I cannot find a lot of data on absorbency by dye manufacturers, will begin emailing them shortly. Key word searches tend to bring up dye absorbency in relation to materials not light...

I am reading through this text http://www.ita.uni-heidelberg.de/~dullemond/lectures/tensor/tensor.pdf and am having a bit of trouble with one of the arguments that is put in index notation. Specifically, equation (3.3). I was wondering if anyone could have a look at it and clear up a...

Hi! I've been trying to model the Saturn V's velocity using Tsiolkovsky's ideal rocket equation, and in the process, I think I may have made a mistake with regards to the specific impulse? I've come up with the following equation, taking the change in gravity into account. (a(t) is the...

Homework Statement Given that -180 <= x <= 180, solve the following equation in radians cosx = -1/sqrt(2) The Attempt at a Solution I'm not exactly sure how to solve this question with respect to the range -180 <= x <= 180. I know that -1/sqrt(2) means that x is 45 degrees in either...

Hi,I am studying mechanical engineering and I am going to apply for my masters in a few months.However, I am wondering if I should do my masters in Advanced Mechanical Engineering or in Fluid mechanics & Power Cycles. What do you think?If I do my masters in something more specific, is this...

Hi all, I need the relationship between cast iron specific heat and temperature in order to perform a disc brake thermal analysis. Where could I get this data? I just need average values for a typical cast iron used for disc brakes. Any suggestion is appreciated Thanks

Homework Statement What is the change in specific enthalpy if saturated water vapor at 100 bar compresses to a pressure of 150 bar? The temperature is constant. Homework Equations None The Attempt at a Solution I used this equation to solve the problem: delta h = delta e + p *...

I am currently in the process of designing a section of pipe in which a fluid will flow within, and would like to determine the specific heat transfer which may occur once the fluid enters the pipe, until it exits. The fluid will be flowing at a constant velocity "V" at a Temperature "T1" at...

So in my lab, I am working with fluorescent bacteria, specifically GFPa1 (green fluorescent protein a1) which are excited with around 500nm light and emit around 516 nm. Forgive me if these aren't correct, it isn't essential for this write-up and my notes aren't in front of me. Is there any way...

Homework Statement Air is cooled in a process with constant pressure of 115 kPa. Before the process begins, air has a specific volume of 0.06 m^3/kg. The final specific volume is 0.03 m^3/kg. Find the specific work in the process. Homework Equations none. The Attempt at a...

The electric intensity E, current density j and specific resistance k are related to each other by the relation please explain

I need to determine the capacitance for a capacitor that I will be connecting in series with a DC series motor to control the current drawn from the battery by the motor. How should I proceed? I have attached the schematic.

Hi everyone I have trouble with this task Homework Statement the specific heat cv is given by c_v =\frac {N_A k_b \hbar^2}{{\Omega_D}^3 {k_b}^2 T^2} \int \limits_{0}^{\Omega_D} \! \frac {\Omega^4 exp\frac{\hbar \Omega}{k_b T}}{{(exp\frac{\hbar \Omega}{k_b T}-1})^2} \, d\Omega I...

Eisenstein's Criterion is stated in Dummit and Foote as follows: (see attachment) ----------------------------------------------------------------------------------- Proposition 13 (Eisenstein's Criterion) Let P be a prime ideal of the integral domain R and let f(x) = x^n + a_{n-1}x^{n-1} +...

I'm having some difficulty understanding exactly what the difference between the definitions of these values are. As I understand it, in terms of solving given problems, you have to use the equation for specific exergy (NOT flow) when solving a problem that isn't a "flow" problem (ie: otto...

Homework Statement 100g of lead, specific heat .0345 cal/g/C at 100 C is mixed with 200 g of water at 20 C. Find the difference in entropy of system at end from value before mixing. Note: I think the book has wrong answer of 1.42 cal/K Homework Equations Before mixing entropy for water =...

Hi all, I am having trouble understanding how to calculate specific charge. I know that it is charge/mass. But what charge are they referring to? For instance an atom may be charged + or - and may not be charged at all. In that instance are we referring to the extra charge that exceeds the...

Hi, I want to passively amplify a specific audio frequency range of a microphone. When I say passively I mean by non-electronic means - no op-amps or transistors. Like a speaker can be designed for specific frequency range - a woofer/tweeter/etc... I presume this works in the other direction -...

Photons need specific energy levels, equal to the difference between two energy levels to excite an electron in an atom. Is this the same case with electrons that collide with atoms?

hello I amm trying to understand the difference between flux and specific intensity of radiation. I understand that one is dependent on distance the other is not, but can you make it more tangible with an example?

Homework Statement I took a test and got it back I'm wondering if my prof. definition is correct. The heat required per unit mass of a substance to produce a phase change is called? A. specific heat B. Specific heat capacity C. latent heat I said it was C. He say's B Please...

Before I say the exact question, this is a inquiry about a hypothetical situation that says the Universe is infinite in both size and age. If possible, I would like a full explanation to what happens to the Universe going beyond the specific question, but I have the question here basically as a...

Now consider two objects,A and B. A has a higher specific heat capacity that B. When both object is subjected to same amount of thermal or heat energy, rise in temperature in A is lower as our common reason(A has a higher specific heat capacity) But what stated by First law of thermodynamics...

Note: If this is the wrong sub-forum for this question please move it. I was not sure if this question should go in the General section or not. Question: I want to create a smooth non-piecewise curve in ℝ^{3} (3-space) such that it's intersection with the xy-plane consists of the integer...

Is there anything like https://www.amazon.com/s/ref=nb_sb_ss_i_0_8?url=search-alias%3Daps&field-keywords=six%20easy%20pieces&sprefix=six+easy%2Caps%2C127&rh=i%3Aaps%2Ck%3Asix%20easy%20pieces&tag=pfamazon01-20 by Richard Feynman for mathematics? I'm looking for a gift book that will appeal to a...

I am curious as to how you find all the various research that has been done on a particular topic? Though I am fairly new to the study of physics, I have been told that prior to becoming involved in a particular research project, you want to look into who else has researched that particular...

I'm going to university next year and I'm strongly considering doing physics. however the I'm slightly concerned because the physics degree at the uni I am going to has very little of the math that i thought is needed for physics. to illustrate my point, in the course there are no PDEs, diff...

What are the relationships between these 3 properties of a fluid and how would you calculate say the density when you know the viscosity and specific gravity?

Homework Statement Assuming the person weighs 980 N on the surface of the Earth, how would you use ratios to obtain the weight of a person at 128 000 km above the surface of the Earth. Homework Equations Fg is proportional to 1/d2 The Attempt at a Solution The answer in the...

I mean why is it that the eye evolved to detect "visible" light instead of, say, microwaves. What is it about the visible light spectrum?

Homework Statement A block of ice has a mass of 150g and a temperature of -4°. The ice is melted by supplying 60KJ heat energy. Determine the final temperature of the melted water. Homework Equations Equations i think can be used: Q = ml and H = mcΔθ The Attempt at a Solution...

I have the following recurrence equation, where C is just some constant: $$ T(n) = 0, n = 1\\ T(n) = T(\frac{n-1}{2}) + 2C, n > 1 $$ Using a top-down approach to unrolling the equation to find the pattern, I get: $$ T(n) = T(\frac{n-k}{2^{k}}) + 2kC $$ Now I want to solve for k and associate...

Homework Statement You have a position working with a group investigating biological mechanisms that determine a predisposition to obesity. Your assignment is to measure the rate that energy is output by certain types of cells when a nutrient is introduced. To begin this study, you have...

Homework Statement An experiment has 3 outcomes. If the experiment is performed 4 times, how many sets of outcomes exist in which exactly two of the experiments had the same outcome. The Attempt at a Solution From what I understand there is a 4-element set with each element having 3...

If I use the answer given in the book for part a, I can get the correct answers for b and c. However, I do not know what I have done wrong in part a? My best guess would be that assuming the blood evaporates at 100 degrees is incorrect? The answer given in the book is 5.1*10^{-3}J

I'm working on a hard sci fi story, so I'm trying to get the technical details right - but I don't actually have a background in space travel, astrophysics, orbital mechanics, etc, so I'm running up against my own ignorance. I've Googled it, read the wiki, read NASA's site, and I'm still...

The question is: What is the minimum radius of curvature of a jet, pulling out of a vertical dive at a speed of v, if the force on the pilot's seat is 7 times his weight? The way I thought to answer this is just to say that, 7 mg, the net force on the seat will be equal to the...

Hello! I am stuck trying to understanding this question. I would be glad if someone could explain it to me. "Each limit represents the derivative of some function $f$ at some number $a$. State such an $f$ and $a$ in each case." Example of a problem: $\displaystyle...

Does anyone know where I can find the specific heat capacity of Diethyl Phthalate? I tried google but couldn't find it. Any help would be appreciated.