Concept Definition and 1000 Threads

Can someone explain to me what 12 grams of carbon 12 is and how to use avogrados number?

Homework Statement A box is pulled across a rough horizontal surface with force F. Each time the box moves a distance D, howeveer the angle of F varies. Which angle causes the most/least amount of friction. An angle above/below/horizontal to the surface. Homework Equations...

I have got a trouble with wave concept suppose wave is passing through a medium ( let it ,just started) suppose there are four points in the medium (particles) A,B,C,D as soon as A is disturbed even by an infinitesimally small distance , B experiences a forces (forces act...

how to solve pulley related rotational mechanics problems... please guide me through... the ques are of the kind... mass is attached to a pulley which is further attched to larger pulley... and the moment of inertia of both along wid their radius is given... mass of the load is...

[Solved] Quick Question - Explain Work Energy Concept Homework Statement Use the work - kinetic energy theorem to find the force required to accelerate an electron (m = 9.11 x 10^-31 kg) from rest to a speed of 1.50 x 10^7 m/s in a distance of .0125 m. Homework Equations W = Fx...

I have learned that the concept of Center of Mass is universal and is applicable everywhere. As per Einstien's Mass-Energy Equivalence there should be a concept of "center of energy" also? For example if I annihilate electron and positron center of mass-energy should apply. The position of...

i've heard that in a loop the loop environment when the object goes to the top (upside down), gravitational force (mg) will equal to centripetal force(mv^2/r) can anyone explain why this is.

i have a concept question that i can't seem to get anybody?? Know?? Lets say you and a friend are wacthing tv and see an astronaut on the space station let go of a pen while he turns to get some paper. What happens to the pen when the astronaugt let's go of it? Your friend says its because...

Homework Statement A penguin stands at the left edge of a uniform sled of length L, which lies on frictionless ice. The sled and the penguin have equal masses. (a) Where is the center of mass of the sled? (b) How and in what direction is the center of mass of the sled from the center of mass...

Can anyone help me to know that if General relativity explains the perihelion of mercury or the CMBR... If so,how?

concept of a "basis" for a vector space I do not understand the concept of a "basis" for a vector space. Here's an example from my practice final exam: Suppose U and V are subspaces of the real vector space W and {u1} is a basis for U and {v1} is a basis for V. If U intersection V = {0}...

http://p14.freep.cn/p.aspx?u=v20_p14_p_0711201047589252_0.jpg Formula: http://freep.cn/p.aspx?u=v20__p_0711201059233972_0.jpg 1)I need to find out V(\theta). But I remember that r\theta<dot> = \omega = V(\theta) Something seems like contradict Where my concept wrong? How should I...

Hi :) I was referred here from the xkcd math forums... Basically, I'm looking for a gift for my mathematician boyfriend. He's a voracious reader and has pretty much devoured every single math book in print, so a book is out. I was thinking of some math-based art would be cool, however...

Please HELP...Don't Understand Simple Concept on Riemann Sums Can someone please explain this to me... The number of subintervals in a partition approaches infinity as the norm of the partition approaches 0. That is, ||Triangle|| approaches 0 implies that n approaches infinity. I thought...

1. One question ask "Which statement below regarding the First Law of Thermodynamics is best? Select the correct answer." One of the wrong answer is "A system can do work externally only if its internal energy decreases. " What does it mean do work externally? 2. Another question ask...

[SOLVED] Concept Question Homework Statement Q2: Suppose rain falls vertically into an open cart which is rolling along a straight track with negligible friction. The speed of the cart a. increases b. decreases c. doesn't change Q2: Now that the cart is full of water, you poke a...

Hi all, I have some questions about the concept of subspace of linear transformation and its dimension, when I try to prove following problems: Prove T is a finite dimensional subspace of L(V) and U is a finite dimensional subspace of V, then T(U) = {F(u) | F is in T, u is in U} is a...

Conventional turbocharging is done from the manifolds. Or as close to as possible. In the last few years, a company (STSturbo) came out that designed a system for rear mounted turbos, that seems to work well. What I am ultimately trying to figure out is the most efficient way of...

I'm sure you've hear or seen this. Its a device that has two bowl shaped mirrors on top of each other, facing each other and the top bowl has a hole cut in the top. The device creates a mirage of any object placed at the bottom that seems to levitate above the hole. How can this phenomena be...

Hey, I had a basic conception question about projectile velocity. When a projectile reaches its highest point, does the velocity of the projectile equal 0 or does it equal the initial x velocity? I know that Vy=0 at the highest point of a projectile's trajectory, but I'm not sure about the other...

Homework Statement Well pretty much i am just starting on my concept quilt and my teacher gave us 9 types of forces that we learn well studied and i need help to understand what she wants me to do. these are the types: Coefficient of Friction contact f Field F Force Diagram Kinetic...

Two forces, of magnitude 4 N and 10 N, are applied to an object. The relative direction of the forces is unknown. The net force acting on the object __________. _____ can anyone please explain to me why the net force can be 10 N ?? thanks in advance.

The standard explanation for diffraction patterns from a single slit employs Huygens Principle and the production of secondary wavelets to form a new 'front'. These fronts reinforce constructively and destructively to produce the pattern. But...if you consider an infinite number of points...

The figure shows a simple pendulum of length L = 54 cm and mass m = 2.4 kg. It's bob is observed to have a speed of vo = 4.8 m/s when the cord makes an angle θo = 24°. What is the speed of the bob when it is in its lowest position? I'm having problems with this type of problem, its a new...

Ok, my book has the example int from -1 to 2 of dx/x^3 this gets split into int from -1 to 0 of dx/x^3 and int from 0 to 2 of dx/x^3. Now, he had previously determined that the second integral returned positive infinity (diverges) by taking the lim as b approaches 0+. So, the book...

Homework Statement (hopefully all can be read) Homework Equations p = mv impulse = m(change in v) The Attempt at a Solution Top Left: My initial guess is they should all be the same since all cars on the roller coaster feel the same affect of gravity for the same distance...

Hi, I'm trying to understand this concept in order to explain it to a child. Let's say I have a battery with a copper wire attached to each end of the battery terminals. No bulbs, no resistors, etc in circuit - just a wire. The battery creates an EMF that moves the electrons in the copper...

Hi, I have wanted to ask someone this for so long, but I know its stupid. Is there a maximum frequency as a side effect of a maximum speed of light? Thinking of light as a pure wave and at a fixed amplitude, it is going to have to travel the distance dictated by the amplitude and frequency...

Concept question--exponential function derivatives (calc II) [FONT="Times New Roman"]Ok, so there is an example on my textbook that asks for the derivative of y = x^2. --after applying ln on both sides, if finally gets to the lny = xlnx step. But after this step, it just states y'/y =...

Hi! I have designed a new concept engine and hope that I can get some useful feedback. http://www.geocities.com/rotarypulsejet . The design is quite radical and I would appreciate any comments that you might have. django

This is the material i read from textbook, and it doesn't make any sense to me! can somebody please help me out if they can understand the concept: To understand electromagnetic induction, we need to reconsider the concepts of electric and magnetic fields. A dc current I flowing through...

I was reading about time dilation and say if we have an inertial S that moves with velocity v in the x-direction with respect to an inertial frame S'. In S' we shoot a light towards a mirror and measure the time from when the original flash takes place to when it returns to it's origin giving us...

Im really having trouble wrapping my mind around the topic of maclaurin series, my problem requires me to find the maclaurin series of f(x) = 1/(1+x^2), then use that to find the maclaurin series of g(x)= arctan(x)...i don't even know where to begin.

Hi guys, I find it quite difficult to visualize torque. The picture I use as reference could be found here. http://hyperphysics.phy-astr.gsu.edu/hbase/tord.html I have had this disk with spindle thing & had tried rotating it. But I did not feel anything in the direction of torque.(red arrow)...

This is a concept that has always eluded me. I'm a Biologist who works in the Pharmaceutical Industry and I need to get a better understanding of Biophysics with respect to enzymology, specifically with regards to crystallography, electron microscopy, and catalytic site binding physics. I...

When an aircraft begins to nose up the effects of gravity begin to slow its velocity. By dividing 100% by 90 degrees you get the number 1.11. So for each 1 degree incline the force of gravity increases by 1.11%? So at 1 degree the force of gravity is 1.11% 45 degrees the force of...

Homework Statement Prove the following useful fact: the least-squares fit for a line through any set of points (x_1,y_1) ...,(x_N, y_N) always passes through the "center of gravity" (x-bar, y-bar) of the points, where the bar denotes the average of the N values concerned. [Hint: you know...

how can an elementary particle like a photon be massless? How can physicist measure and detect a photon if the don't know its inherent properties? I know a photon travels at the speed of light , but wouldn't you have to know a particle mass , in order to know its speed? Or are physicists...

Any interested in this topic?

In problems which have a pulley with a certain mass and radius, and a massless string over it, we often consider the tension of the left part of the string different than the tension of the right part of the string. I thought that since the string is massless, the tensions should be the...

Homework Statement In which of the following situations will light from a laser be refracted? a. traveling from air into a diamond at an angle of 30° to the normal b. traveling from water into ice along the normal c. upon striking a metal surface d. traveling form air into a glass of...

How should I think about the concept of phonons? As I understand it, it is a wave which propagates with a speed similar to sound and models the movement of atoms in crystals. However how many atoms per phonon? And isn't phonons meant to be analogous to photons which are single units hence one...

1st question Ohm's Law is R = V/I; however there is another law that states : R = p (L/A) (the p should be a rho, i know) so this means that V/I = p (L/A) ? 2nd question A resistor in a circuit can have a smaller current in it than the actual wire because of a higher resistivity...

Hi, I am curious to kow about this smoothing concept that I've seen mentioned somewhere but do not understand. It would be great if someone could explain it to me, preferably through a solution to this problem. Thanks for any comments. (Latex did not generate in the preview, so if it seems there...

I am studying 'Integration' These are the questions I have been thinking of, but i still did not get it. 1.I understood the basic concept of dx and dy But I don't know what exactly does dx stand for in the definite and indefinite Integrals. \int x^3\, dx\right)2. I have read a proof in...

concept of resistive touch screen, anyone an IEEE member? hi, i am having a problem with my 8 wire resistive touch screen the cursor keeps drifting about due to analog noise i suppose i would need to program an algorithm to clean up the noise to keep it stationary. i have tried putting a...

Please help, I'm confused with an "easy" concept. Suppose you drop an object off a cliff. Does increasing the mass of the object you drop decrease the time it takes the object to reach the ground? (Assume that air friction is neglected) Is this true to infinite extent? So if there was no air...

i just don't understand why an object will experience buoyant force equal to the weight displaced when it is partially or wholly immersed in a fluid.I don't want to memorize this,i want to understand and get the idea.But i just don't seem to understand.

Hi My thought might be a bit weird or maybe childish, but I can not find anything to object it or to prove that it is wrong. As a basic definition of a straight line that it is an infinite number of points that are connected together. Regardless the length of that straight line, it consists...

Hello, I have read over many textbooks and websites (including posts on this forum) relating to the concept of tension but I am still a bit confused. Many sources seems to only define tension rather than explain it. They seem to assume that you know it the way you know 1+1 =2. Here is the...