Basics Definition and 379 Threads

Hi, I am going to attend A level exams as a private student by january 2018 in the subjects of mathematics, physics, chemistry and biology. I have planned to study 2 hours per subject in a day. By evening I would go to coaching classes in all subjects except biology, that would be 3 hours of...

I've been trying to get a rough understanding of what renormalization involves (in a particle physics context; I'm aware it has many other applications eg. condensed matter) but it hasn't quite clicked yet. The things I have in my head so far are as follows: - A particle will be surrounded by a...

I don't know how to calculate the voltages at the bases of every transistor shown in the lower row of that picture (~3V (2.9..V), ~2V, ~1.8V). Any help would be appreciated! - I'm currently trying to figure that out... The other thing I don't really understand: Why do the transistors in the...

So I have been preparing to transfer into a physics program at the university from a community college. However, I am debating on whether I should go back and cover the material from my previous physics courses to build a strong foundation or if I should start learning the new material that will...

is there any difference and why ? I have a ball valve with 100 psi jet fuel on one side and atmosphere on the other end ? Is there any difference if o have 100 psi and the valve all the way open vs. say 200 psi and only half way open . Please explain ?

1. Give a formula for the values on m such that z^m=z z=cos(7pi/6)+i*sin(7pi/6) 2. If i use de movires i get 3. m*7pi/6=7pi/6 + k*2pi But then i get the value that k=12/7, Which is the wrong formula. The correct answer is 1+12k for k=0,1,2...

Hello, I got the following diagram, shown below, and I have to derive its transfer function. I think I have a general misunderstanding about the transfer functions. What I think it is, is: output/input basically. As input is the whole block of things that affect the output. This is the system...

anorlunda submitted a new PF Insights post AC Power Analysis: Part 1, Basics Continue reading the Original PF Insights Post.

Homework Statement [/B] Hi all, these were two even numbered exercises in my C++ textbook. I am self teaching the language so I am trying to get some of the basics down. 1. Would the following snippet of code best be described as an example of Polymorphism or Inheritance? class Shape {...

klotza submitted a new PF Insights post The Basics of Positron Emission Tomography (PET) Continue reading the Original PF Insights Post.

Hello I am currently learning some of the basics of number theory, and struggling to understand this Theorem. Could someone please explain it with maby a simple example? :) THRM:(Number of polynomial zero mod p and H) Let p be a prime number and let H be a polynomial that is irruducible modulo...

Hi guys, I'm a newbie in quantum physics and it has blown my mind so far. I feel a bit confused because it seems very unintuitive, but I'm ready to learn more and I need some help on this forum. I have few questions. 1) I red that the wavefunction of an electron is spread all over the universe...

Homework Statement Homework Equations p.q+p.r The Attempt at a Solution I've expanded p.(q+r) to give p.q+p.r. The magnitude of p is 3, and since ABE is an equilateral triangle, the magnitude of q is also 3, right? So then p.q=9, but the answer scheme states that p.q=4.5. I'm still pretty...

I've been doing some thinking about the different levels of mathematics I've gone through in high school. For a little context, I'm a current undergraduate student highly debating majoring in astrophysics. I just finished Calculus I with an A- and I'd consider myself very proficient in it. I...

Hello pf, I have been trying to grasp the concept of RA. I have read through a few books and I know that it is measured eastwards from the point on the celestial sphere where the Sun crosses the celestial equator at the vernal equinox. I just want to check I understand this correctly. Does it...

Hi folks, Firstly a little background, I work for a company that manufactures gas pressure regulators. Last year I was a machinist studying for my HNC in manufacturing engineering. Since passing work has given me the opportunity to work in the product engineering office as a product tester and...

1. Introduction Pressure of a fluid exerts thrust on each part of a surface with which the fluid made contact. Each forces distributed over the area have a resultant magnitude and direction that is very crucial. For a horizontal surface, the pressure does not vary over the plane. Thus, the...

Can someone explain to me what are real roots?

Variable; A symbol for a number we don't know yet. It is usually a letter like x or y. Example: in x + 2 = 6, x is the variable. [mathsisfun.com] Q. Why is it called the variable? This seems to me to imply that its value varies. In the above example it seems to me to simply be the unknown...

I am having some issues understanding the fundamentals of Java and OOP. In simplest terms possible with an example can you explain to me what an Object, Class and Method are? I am confused on what these actually are. Thank you

In my head, I'm using (delta)(gravitational potential energy) as an analogy to the (delta)(electrical potential energy). So, with a DC circuit with loads connected in series, we can observe a voltage drop across each load. Now, because the current remains the same throughout, it must mean that...

Q. Is the following a correct definition of waves? “Waves are vibrations that transfer energy from place to place without matter (solid, liquid or gas) being transferred. Think of a Mexican wave in a football crowd - the wave moves around the stadium, while each spectator stays in their seat...

Q. Regards infrared radiation, conduction and convection, is infrared radiation the starting point, the fundamental source of heat energy (thermal energy), and the fundamental source of the other two? I’m thinking that the Sun predates the Earth by 30 million or so years so the first heat...

Given a simple DC generator with a single loop in the presence of a magnetic field such as the one below, typically, the analysis involves how each rectangular loop's terminal ends up on opposite sides of an armature housing each of the coils. The analysis is fairly straightforward to then...

From gcsescience.com; "Heat can be transferred by conduction only in solids." Q. Doesn't conduction take place directly prior to convection (when a radiator heats up a room)? If my cold hand came into contact with the warm radiator this would cause conduction; why isn't it the same for the...

The specific heat capacity is the amount of heat energy needed to raise 1 kg of a substance by 1 °C. Q. So the specific heat capacity of water is 4.184kJ (given that 1 Cal (large calorie aka the kg calorie aka the food calorie) is required to do the same, ie, raise the temperature of 1 kg of...

Is the following correct? Temperature is the measure of how hot or cold something is; not how much thermal energy it has. Examples; 1 kg of boiling water has a temperature of 100 degrees C and has heat energy of 4.184 kJ (the specific heat capacity of water). 1 kg of lead heated to a...

Q. When energy transfers from one form into another it is called ENERGY TRANSFER - eg, chemical to kinetic in a car, electrical to light in a lamp – but what is it called when energy leaves one object and enters another (eg, from a warm hand into a cold hand) but the energy doesn’t change from...

bapowell submitted a new PF Insights post Inflationary Misconceptions and the Basics of Cosmological Horizons Continue reading the Original PF Insights Post.

Please suggest a book for basics of electronic devices subject.

1. When we walk we push backwards against the ground with our feet and the opposing force pushes us forwards, is this opposing force friction? Or is it the Earth pushing us in response to us pushing it (with our foot) re Newton’s 3rd Law of Motion? Is there one pair of interaction forces...

1. Is 'surface gravity' the same as 'gravitational field strength'? 2. It seems to me that the 'g' in the formula w = mg sometimes refers to acceleration due to gravity (measured in m/s^2) and sometimes refers to something else that I've not quite grasped yet (measured in N/kg) ; what is the...

I read this description of thrust on gcsescience.com; "Hot gases are forced downwards through the rocket's jets which pushes the body of the rocket upwards.This is an example of Newton's Third Law of Motion. " I've learned already that Newton's 3rd law states that for every action there is an...

Are the following definitions of weight valid; The force of gravity pulling on a mass? The force between two bodies due to the force of gravity? Q. Does weight only apply to the force due to gravity on a body in relation to a planet (or satellite, asteroid etc), eg, a man standing on Earth or...

The safe path for me is pre-med, which means biology. For career purposes, I imagine it's in my best interests to double major (Bio, computer sci, maybe a minor in business or economics). I've been told that having tech schools will make an M.D. even more valuable. Which reminds me-- I've been...

I just feel like rambling on, so I will. Perl gets a bad rap for being hard to read or maintain. But, in reality it is just as easy to read as C or any other language. What is difficult about perl are the regular expressions, which are notoriously cryptic. But, regular expressions are...

I'm getting confused with the type of bonding (1) between the nucleotides and (2) between the nucleotide and the "sugar phosphate backbone". This diagram: http://tigger.uic.edu/classes/phys/phys461/phys450/ANJUM04/DNA_helix.jpg Shows hydrogen bonds between the nucleotide bases. But then Wiki...

Okay as suggested by one of the 'Staff:Mentor' , advised me to have a clear sense of "mass", "weight", "speed", "velocity", "force", and "acceleration" and the mathematical relationships between them. I know all of them, but it's not accurate/exact. P.S.: Ofcourse, I can google search it, but...

Im a recently graduated mechanical engineer and i just joined a construction company as an M & E engineer. i want to know the basics of electrical knowledge that a mechanical engineer should know. please advise me on this topic. i am willing to learn and expand my knowledge.

Homework Statement I have recently learned about the boost SMPS and and have built a circuit to investigate the waveforms and levels for Vout, [L] and [C] for different mark space ratios. the circuit consists of a 95uH inducotr, diode, 47uF cap, 70 Ohm load, a FET who's gate is controlled...

Homework Statement Two small plastic balls hang from threads of negligible mass. Each ball has a mass of 0.14 g and a charge of magnitude q. The balls are attracted to each other and the threads attached to the balls make an angle of 20.0 degree. with the vertical. The balls are 2.05 cm apart...

Hi guys! Sorry for a really dumb question, but I want to study particle physics more in depth, since our university course didn't really satisfy me that much (and, when it comes to physics, I want to know everything I can get to). Can someone give me a general list of things I should know and...

Ahoy. Two things ought to be known prior to your reading my terrible post: 1. This is my first post. 2. I don't know very much about this whole business (though time and passion suggests I should) Considering its my first post, let's start at the beginning: Now, I've been reading a whole...

I'm on my first pass through special relativity and I can't remember the math that would take me from: (∂τ/∂x') + (ν/(c2-ν2))(∂τ/∂t) = 0 To τ = φ(ν)(t - (ν/(c2 - ν2))x') Any help would be appreciated. Also, sorry for the terrible format, but I haven't taken the time to figure out how to do...

Hi PF I am reading an old Rovelli paper http://arxiv.org/abs/gr-qc/9603063 Rovelli computes the entropy of a black hole. He says two things. a) A state is described with an equivalence class of s-knots. b) the entropy of a black hole can be computed by counting the number of the intersection of...

I have been trying to get my head around the basics for these four (Carbohydrates, Proteins, Amino Acids and Lipids) for about a week and I just don't understand the basic structure, formulas and such. Help?!

I mean why is f=ma? why not m0.123a1.43 or some random non integers? I hope you understand that my doubt doesn't limit just to force or energy or velocity e.t.c. it also extends to area of a square,circle e.t.c and all other formulae i think whole thing starts with direct proportionality.

So I'm currently a senior in high school in the U.S. and I'm hugely interested in mathematics. I was accepted to the University of Chicago (my top choice) and I'll be matriculating there in the fall. My background in math is a bit of an odd one. I used to hate it as a kid, but I always read...

Sir, i need some basic information about analog vs digital signal/information transmission. i have few Questions and and idea to discuss weather its feasible or not. [Q1] can digital data requires same bandwidth as analog data contains as if i convert analog information to digital using DAC and...

Recently, I was trying to control the strength of an electromagnet with PWM over a MOSFET or IGBT with an Arduino/microcontroller. It worked but I burnt multiple MOSFETs/IGBTs while testing it, after certain time... so something must have gone wrong... I'd like to build a simple circuit, to...