Concept Definition and 1000 Threads

This is a snippet from a mock encyclopedia which i will not link to. While I am not endorsing this viewpoint, I want to understand, what is fundamentaly inaccurate about what is being said? " In reality, the highest level of education required to comprehend the theory of dark matter is...

Or not?

What is the greatest acceleration a runner can muster if the friction between her shoes and the pavement is 90% of her weight?

An object is moving with an initial velocity 5m/s, if I'm applying a force against it and it stops after a displacement. So the work done is equal to 0.5m(0)2-0.5m(5)2 A stationary object, 0m/s, if I'm applying a force to it and it moves with a velocity of 5m/s, and stop after the force...

What if we don't NEED to use any force whatsoever to propel a vehicle? What if we could negate the net external force and just keep the vehicle going with a constant velocity with the appropriate magnitude? But what could we use to propel the vehicle at any given time and not add any other force...

Homework Statement Given the electromagnetic wave traveling in the y direction at velocity c: B = +cEo sin(k y − ω t) ˆi. a) What happens to the ratio of the electric to magnetic field if the angular velocity ω of the wave is decreased? Does it decrease, increase, or remain the same...

Homework Statement Describe the domain of definition that is understood for each of the functions: (a) f(z) = \frac{1}{1 - |z|^2} (b) f(z) = \frac{z}{z + \bar{z}} (c) f(z) = Arg(\frac{1}{z}) (d) f(z) = \frac{1}{z^2+1} Homework Equations A function f defined on S is a rule...

Homework Statement "A standing wave in the form of a string attached to a driven tuning fork is created. We then move the furthest boundary point to a node somewhere along the string. The node of course was originally at rest by definition. The string behind the node with the boundary point...

Homework Statement this is just a personal question that i have. i know that to find the magnitude of any vector with components, say, 3i + 4j, you need to add 3^2 + 4^2 and take the square root. i know this comes from the pythagorean theorem so, my question is, how is it possible to use the...

Hi all, a few days ago our lecturer has told us something which i do not really understand, and i was hoping if someone can clear up the issue for me. The following is what was said: we have a motor and we have a pump, the pump and motor shaft is joined by a coupling. If there is a...

Homework Statement Sketch 0 \le arg z \le \frac{\pi}{4} (z \not= 0)The Attempt at a Solution I know from my book that his is a punctured disk aka deleted neighborhood only because it says so and because it is in the form of 0 < \mid z - z_0 \mid < \epsilon. I honestly have no clue...

Hi all, today our lecturer has told us something which i do not really understand, and i was hoping if someone can clear up the issue for me. The following is what was said: we have a motor and we have a pump, the pump and motor shaft is joined by a coupling. If there is a misalignment...

Hi This is regarding the pinhole camera concept regarding apparent angular size. If we take the simultaneity train and assume the lightning strikes are behind translucent ends of the observers car and that the observer has two pinhole cameras facing forward and back: In the view of the...

The more rapidly voltage across a capacitor changes, the more current will flow (the higher the frequency, the greater the current). Questions I was wondering, does the statement above deal specifically with AC circuits by the statement Or does this statement apply to DC circuits also...

what exactly is the number zero? I mean, the number 0 seems to negate the absence of meaning in the digital world just like God negates it in the analog world. any ideas?

Homework Statement A ball is thrown straight up into the air. If we do not ignore air resistance, the acceleration of the ball as it is traveling upward is...? a.) 9.8m/s^2 b.) greater than 9.8m/s^2 c.) less than 9.8m/s^2 d.) zero Homework Equations n/a The Attempt at a...

Homework Statement How many significant figures in each?: -214 -81.60 -7.03 -.03 -0.0086 -3236 -8700 I don't quite understand this (I'm self studying, need a little help :) ) If got them all right then can someone explain the concept of significant figures? I hate knowing only...

Okay, I understand that voltage is the work done per unit of charge from the electric field to move a charge from one point to another. What does it mean for work being done on a charge? Are the charges being moved by an electric field? If so, why would the electrons move towards the negative...

Would a bird strike impact with an in-flight jet propulsion intake have a significantly less probability of avoiding critical damage if the jet intake was fully idle or non-active at the point of impact? Would the air-flow pattern of an abruptly idled engine perhaps even help by greatly...

Verify special relativity by concept "light clock" Hello. For verify the special theory of relativity most books use a "light-clock": Obviously, the way the light covers, when the clock is moved is bigger, than the way the light covers when the clock is not move. Because speed of light...

hi. I want to know that... who introduced the concept of variable velocity? Aladin

hey guys I've got another problem, any conceptual help and help would the questions would be greatfully apprectiated. thanks Homework Statement From a consideration of the data below determine which of the given species will oxidize Fe to Fe2+: Data Fe2+ + 2e- --> Fe; E° = -0.44 V...

Homework Statement A ping pong ball covered with a conducting graphite coating has a mass .005 kg and a charge -4 microC. What electric field will exactly balance the weight of the ball? Homework Equations qE = mg The Attempt at a Solution I know how to get the magnitude of the...

I came up with this during idle afternoon. Don't know if it's worth something but I wanted to discuss it with someone. Basically, outline of business part is given on the picture Horizontal tori are basically tokamaks and vertical pipes are "fusion combustion chambers" where working fluid...

Homework Statement I'm doing an assignment involving a current balance, and the one thing I don't understand is the currents. I have two separate currents, one labeled "Current in Solenoid" and another labeled "Current in Loop". Now, I know the current in the loop is the part that causes...

Homework Statement Object A and B are placed on a spring. Object A has twice as much mass as object B. If the spring is depressed and released, propelling the objects into air, object A will: answer: rise to the same height as object B Homework Equations The Attempt at a...

Hi everyone.. I've run into a bit of a problem while studying the concept of tension. If a block which had a weight of 100N was to be hung from a rope which in turn was tied to say, the branch of a tall tree what would the tension in the rope be? According to all the textbooks it should be...

Hi, I believe that to make a PMOS work, Vgs (th) needs to be negative but when I give -5V to source and connect it in a source follower mode i.e. vg = -5V, I do get an output. Can anyone tell me how and why? Thanks, - Hemant

Homework Statement Compute the Fourier sine series for the given function: f(x) = -1 0<x<1 Homework Equations http://mathworld.wolfram.com/FourierSineSeries.html The Attempt at a Solution I got: bn = 2 * integral( (-1) * sin(npix) dx) from 0 to 1 = 2*(-1)^n/(npi)...

well this is a really good question which i just thought while playing cricket. A sphere of mass m and radii r(a tennis ball) falls freely from a height of H and angular velocity(clockwise) about its axis omega.Coefficient of restitution is e The coefficient of friction is mu. After the...

Homework Statement Dipole in an Uniform Electric Field: torque is calculated about the position of either charge has the magnitude FLsin(x) = qELsin(x) = pEsin(x). The direction of the torque vector is into the paper such that it tends to rotate the dipole moment vector p so it aligns with...

Homework Statement would you say that "the two forces exerted on the book ar ethe normal force directed up and the weight of the book directed down. These are equal and opposite to one another. By Newton's third law they are a third law force pair, so the normal force is always equal to the...

Nvm, bad question... i deleted it lol

Homework Statement This is the circuit in question. # 31. R1-R3 = 2 Ohms R4=16Ohms R5= 8 Ohms R6=4Ohms i6=1.4Amps Homework Equations V=i*R The Attempt at a Solution I see R5 and R6 as being in series, therefore r5*i6=11.2V r6*i6=5.6V Then I add them...

I was reading this very small section in my physics book and can't seem to come to grips with its concept. It starts off with Newtons shell therem being applied to a particle located inside a uniform shell and that the shell exerts no 'net' gravitational force on a particle inside it. It...

Hello, This is just a conceptual question I have for the image below. http://img22.imageshack.us/img22/7489/44840348.jpg If the switch is turned off at t=0, why is the voltage across the voltmeter=20V? I understand that current in all inductors is zero. But wouldn't at t=0, current would...

I understand the basic concept of how it happens and what it does, but the book I am reading is confusing me a little

When Gas reached almost 4 dollars a gallon I started thinking about how to make a more efficient engine and drive train for cars. I don't intend to protect my intellectual property on this but rather put it out to see if somebody wants to do something with it. Email me for a diagrammatic flow...

Hi, I wonder if anybody can help me in conceptualising an idea for teaching students (16+). I call it dimensionality thought probably that's a bad name. It concerns the fact that we llive and are active at a certain scale - at a certain mass - that distances us both from activities of...

My teacher had a long metal pole (I believe it was aluminum) and said that it was NOT magnetized. He put a magnet up to the side of the pole and it did not stick, and he dropped a marker through the top of the pole and the marker came out the bottom at a normal rate. However, when he took a...

Hi Guys, I have the following circuit I want to analyze: I do not understand by the DC voltage on both capacitors is 3.75V each. The initial charge on capacitor C1 is 5V. I am just trying to understand a basic switched capacitor concept and am stuck here. Any insight would be greatly...

What is time? What is the definition of time? What is this concept of time? Hey all, I asked my Physics teacher and many friends what time is, and non of them had a thought about it, Such a simple question yet difficult to answer. I would like to read your thoughts about time and your answers...

Homework Statement Im am having trouble grasping the concept of complex numbers, could anyone please take the time to explain it. I have asked my lecturer but his help just seems to confuse me more. I have also searched the internet looking for explanations but that is giving me mixed...

Is 'existence' a concept or an actual state? Does it take a brain and its processing abilities in order to conceptualize an external world? It seems to be true. But, does it take a brain and its processing abilities to actualize an external world? Hmmm... Any takers out there?

Hi all, I have a simple question related to electrostatics. We have the concept of electric field which is a vector field and makes sense. I am aware that it is just a virtual concept in fact, defined as force per unit charge, in other words, it doesn't exist. However, I understand the reason...

~~Resistor Concept~~ Hi. I am having trouble with understanding the resistor. What does a resistor do in SERIES or in PARALLEL circuit? My understanding: ( please correct me if i am wrong!) In series circuit, Resistor is a device that reduce the current in the circuit. And according to...

Hello, Let's say I have a group (G,\ast,0) and I define an endomorphism f:G \rightarrow G I know there is a subset H \subseteq G such that: u \in H \\ \Rightarrow \\ f(u)=u Essentially we have defined an endomorphism which, for a subset H, behaves like the identity function. Is this a known...

Concept of an "area vector" when finding magnetic flux Hello, I'm currently learning basic Electromagnetic Induction, specifically induced emf in a loop. According to my textbook, magnetic flux is defined as: \Phi = BA cos \theta Given that the field is uniform and is traveling through a...

Doublethink is a concept of George Orwell's novel 1984. "The power of holding two contradictory beliefs in one's mind simultaneously, and accepting both of them." "Americans tend to define politeness in terms of "friendliness": smiling, telling "white lies", pretending to like people even if...

In class today, my instructor went over conic sections and ellipses (and hyperbolas, although that's irrelevant). We pretty much learned the basics - foci, semi-major and semi-minor axes, etc. However, the equation c²= a² − b² where c is the distance from the focus to vertex and b is the...