Concepts Definition and 403 Threads

I'm trying to understand how to solve PDEs that are Sturm Liouville problems. I've read a couple of presentations about this, but I'm lost as to the implications for the solution process. Most descriptions discuss putting the second order differential equation into a Sturm-Liouville form...

I'm trying to understand the concept of a Gradient vector, and it seems I'm having trouble visualizing certain stuff. So, I was hoping if someone could resolve some of the questions I'm having on my mind. Okay, so I'm considering a real-valued function z = f(x,y) which is smooth, i.e., its...

Hello, I am trying to investigate single-stage rockets and I've come across a particular situation I don't know how to handle. The situation I have is that the rocket in question is burning it's fuel not at a constant rate but at a rate R(\dot{m}). So to find the equations of motion shouldn't...

I have several questions about capacitor's concepts. Q1)What does battery really do in charging a capacitor? Q2)Uncharged capacitor doesn't mean the plates don't have any charges? Q3)During charging,the developing electric field between the plates does have any effect in charging? Q4)When...

Homework Statement Suppose you have a friend who wants to go bungee jumping for her birthday. She wants to jump off a high bridge over a river and be able to touch the water below right when she gets to the bottom of the bungee cord extension. You want to double-check all the physics of...

So we're covering RC circuits in my physics class and I'm having some trouble with the concepts. When you have a circuit with a resistor and a battery, current passing through the resistor produces a voltage drop. If the battery is zero for our potential, the battery imbues the circuit with...

Author: Nouredine Zettili Title: Quantum Mechanics: Concepts and Applications Amazon Link: https://www.amazon.com/dp/0470026790/?tag=pfamazon01-20

Hello. As I've said a few times before on this forum, I'm 16 years old and I'm teaching myself physics because in my school everything is taught too slowly for my taste. I have a pretty decent grasp of differential and integral calculus of one variable and I have a solid understanding of...

I've learned some concepts in my Electric Circuit Analysis course: Ohm's law KCL + KVL Voltage Division (derived from Ohm's law + KVL) Current Division (derived from Ohm's law + KCL) Y-Delta transformations Nodal Analysis (derived from Ohm's law + KCL) Mesh Analysis (derived from...

I took a thermodynamics course last year and I know which topics confused me (fugacity for example) but I'm curious now in general about things people struggle with. Please add the time at which it confused you (first time undergraduate class, graduate class, etc), or describe how it was...

I understand many classical physics concepts but I feel like my understanding of the concepts are all scattered. I can't seem to make links between concepts. For example: I understand momentum, forces and energy, but I have trouble making any links between the ideas (other than the link that...

Okay so if I'm correct, Hubbles red-shift relationship was first established via expecting a doppler shift - a change in the observed wavelength (perspective of reciever at the time of reception) with respect to that emitted (perspective of the emitter), caused solely due to the respective...

Hi, I am trying to read the chapter 2 of the book "Speakable and Unspeakable in Quantum Mechanics" from J. Bell. I have got some doubts and I would be glad if someone could help me. I see that λ is a vector that makes the role of the hidden variable. All the tricks about the angles between...

A few years ago I made an exploration of some simple concepts that led to some fun facts and a sequence of numbers I later learned is quite well-known. It may even rival the Fibonacci sequence in its fame. I thought it might be nice to collect my notes and present my findings here. I thought I...

Some silly questions I've just never been able to figure out, and it really bothers me when I don't know if something is a concept like speed, or just a way of describing something else and not in itself tangible. If anyone could take the time to clear these (or some of them) up for me, it would...

So I love the Physics of Superheroes, I use it a lot when I teach. Today I did a lesson on work and energy using scenes from Spider-Man (climbing the wall for Work - > Gravitational PE, swinging from the top of the building for Gravitational PE -> KE) and Spider-Man 2 (stopping the train for KE...

Firstly, I have just read that at 25degC, 1 out of every 10,000,000 H2O molecules breakes into H^{+} and OH^{-}. If this true, then would this be correct: Assuming no ionization occurs yet.. If 1 liter of H2O = 1000grams, and 1mol H2O = 18.015g, then by Dimensional Analysis...

my question is , what's the fundamental difference difference between positive and negative charge? i mean in what way a positron and a electron are fundamentally different? is it spin properties or others?

Drawing on a number of threads in this forum, and my very limited understanding of relativity, I am intrigued by the following thoughts: If I have understood correctly, in GR, c is supposed to be only a 'local global constant', and not exactly a Universal constant. Meaning that, two distant...

Hi, I'm unsure if I'm posting this in the correct place, so apologies in advance if not. I looked at the study board, but the post template doesn't apply to my question. I'm a layperson who had previously only read popular science books on QM, but has recently been watching some more...

Homework Statement can you judge the diagram I want to make sure i have the forces being exerted in the correct order. Homework Equations The Attempt at a Solution

Hi Guys, I have a Year 11 Project weighted 15% of my year mark due in 5 weeks. For my project I've decided to build a classic combustion potato gun. This gun will consist of pvc piping, barrel, Lantern lighter, any other components and of course hairspray (combustion) Anyways It is still only...

I have information that time slows down in space. For example if an astronaut is on the Moon or in space for one year, he didn't age. If he returns to Earth he is as young as he left Earth? I don't understand this. If someone travels to another planet (3 months journey through space), I...

Homework Statement I'm designing a pratt bridge for class that looks like this: http://www.garrettsbridges.com/photos/pratt-truss-bridge/attachment/pratt-truss-bridge-2/ I have a two dimensional drawing of one side of the bridge. 2. Homework Equations / 3. The Attempt at a Solution...

Homework Statement How is the field of mathematics which focuses on defining the calculus concepts (such as limits) using the set theory and/or sequences called? Where numbers are seen as discrete, and concepts like limits are defined in these terms. Homework Equations The Attempt...

i.e. anatomy 101, biochem 101

Everybody says that inorder to master physics we must be thorough in our fundamentals . So can anyone explain me wat is meant by getting fundamentals correct and how to study physics conceptually

Microwaves heating is often referred to as dielectric heating, but I'm not sure why this seems so special to specify of all the different thermal radiation frequencies. Doesn't infrared heat the dielectric material as well in a similar process? Isn't radiation heat transfer common for a wide...

Homework Statement It asks me to work out the work done by force P and it tells me that the ball m has a CONSTANT speed during its displacement. That diagram is taken from a book which has already solved the excercise without using the concepts of energy and conservative forces. It used a...

Please suggest me some economic concepts to learn - the more important, the better. I'm self-teaching economics, and want to find more concepts to learn.Here are some of the ones I know as of now (might edit it as I learn more): Factors of production and final product (inputs and outputs) The...

Sorry about asking such a basic question but I'm having a brain fart. So if I have a sample of 3 iid random variables X1, X2, X3, I know the median is just the middle value. So does that mean that the 80th percentile is the third largest one and the 40th percentile is the smallest one? If i...

Hello, I am in Grade 12 physics class and I have been given a open ended project; where we are required to build/create a machine which would involve at least 6 of the physics concepts: ramps, pulleys, levers, transfer of momentum/energy, projectile motion, circular motion, stored elastic...

Homework Statement Sketch the graph of a differentiable function f such that f(2)=0, f' < 0 for -infinity < x < 2, and f' > 0 for 2 < x < infinity. Homework Equations The Attempt at a Solution I have answered this question correctly, but what interested me was that in the...

Homework Statement I'm staring down a concept homework assignment that is giving me fits. We are just moving into relativity. 6) The quantity γmc^2 represents... a) the rest mass energy. b) relativistic kinetic energy. c) total relativistic energy. d) relativistic momentum. e) None...

They say that electrons move from the higher potential to the lower potential. For example, in this situation. Q1 and Q2 are negative charges and Q3 is positive. But, the equipotential is lower on the Q1 and Q2, so by definition of potential difference, the electron would go from the...

Hello there, I was just reading some articles on Wikipedia.org and found an article on proton decay. I will quote a part of it: How would that be visualized? I've got a basic understanding of particle physics, but these concepts seem rather advanced, yet, I insist on wanting to understand...

I have taken courses in math up to calculus 2, after which my math ambitions came to a quick hault. I would like to pick it back up and attempt to casually learn some math on my free time. So I would like to know the sequence/order of math concepts that someone would normally take at a given...

Homework Statement i need help with this statements on momentums (we have to choose whether is yes or no) A small cart carrying a small physics student (total mass = M) is designed to coast into the wall (at speed vi) and bounce off traveling in the opposite direction (at speed vf). In...

I'm wondering about linear particle accelerators. THey're something I've been researching for a while, and I found two conflicting ideas. On one source, it states that all you essentially need is a long tube and a high voltage power supply. So, if I had a voltage multiplier and assigned the...

Just a small rant to start. My DE/LA class is absolute nonsense. I am really wishing that I taken each class separate because this class is making me and many others lose the big picture. For instance, this class doesn't teach linear transformations and diagonalization both of which I keep...

While reading "The Elegant Universe" by Brian Greene, I got stuck on the chapter about quantum geometry where it suggested that there are apparently 2 concepts of distance. I recall something about measuring distance with a probe traveling across the distance at a fixed and known speed and...

Hi everyone, I'm having some issues understanding how to approach (conceptually) a problem where there is a box with a ramp with static friction. The scenarios that are problematic to me are when you are pushing with a force horizontally and perpendicular to the surface. It's not a...

A rocket ship of length L (in the rocket's frame) leaves the Earth at speed v. A light signal is sent after it which arrives at the rocket's tail at t'=0 and t=0 according to Earth clocks. My question is: Why is it that the total time (according to earth) for the signal to get to the head and...

Homework Statement I can do the math work, but I always overthink these multiple choice concepts. A block is attached to each end of a rope that passes over a pulley suspended from the ceiling. The blocks do not have the same mass. If the rope does not slip on the pulley, then at any...

Hey, My professor introduced circular motion this last Friday in his lecture and I've spent the weekend trying to figure out the basic concepts behind it as well as the different formulas that are used. I've had a lot of trouble with this and any help would be appreciated.

I've observed that by putting great effort into learning concepts which initially seem incomprehensible or very difficult to conceptualise, even if it may at first appear like I made little or no progress, I usually end up with enhanced cognitive abilities which extend beyond the concepts I was...

I am having trouble conceptualizing and drawing situations that involve glass, or any other medium that light travels through and doesn't totally reflect like mirrors. For example, say I have an object in a glass bowl of some sort. I know that the light rays will travel until they hit the...

I am currently taking Biology 2 and learning about Micro organisms like bacteria and fungi. However, I find both listening to my professor lecturing and reading the material draining and only slightly interesting. Its like learning another language where nothing seems to hold much significance...

a particle of weight W is attached by 2 light inextensible strings each of length a to 2 fixed points,A and B, distant a apart in a horizontal line. write down tension in either string. one of the strings is now replaced by an elastic string of the same natural length and it is found that in...

hi, I was reading an article about graphene and I came across some concepts I am not familiar with. I was just wondering if someone could help me understand them: The article says that charge carriers in graphene are massless fermions that are described with a Dirac-like equation rather than...