Short Definition and 505 Threads

A railroad car has crates in it with a coefficient of .5 w/ the car's floor. The train is moving at 22m/s, how short a distance can it be stopped w/o letting the crates slide? Fnet = 0 because you don't want sliding. a = coefficient of static friction x gravity When I solved for a...

I have not yet read anything about special relativity, so these questions may be naive. Here are my questions (very much related to each other): 1) Is it assumed in the physics community that dark matter is really matter? If so, why? 2) Can't it be that "dark matter" is just a dent in...

Homework Statement What is the difference between an open circuit and a short circuit? Open circuit has no current, so does that mean any resistor in series with it, has no current ,so it can be ignored for analysis( v=ir so 0 current means 0 V) for finding let's say the Thevenin...

Hi everyone Books mention the Open Circuit and Short Circuit tests on a synchronous generator in order to determine its synchronous impedance. One observes that the Short Circuit Characteristic (plot of short circuit armature current versus field current) is a straight line all the way...

how to not short circuit an induction heating coil Just wondering about induction heating coils and how to not short circuit one. basically, if i hook up one end of the coil to the positive and one end to the negative (DC) i assume that i will be short circuiting the connection and also...

Homework Statement Let g(5)=-3 g'(5)=6 h(5)=3 h'(5)=-2 Find f'(5) for f(x)=g(h(x)) Find f'(5) for [g(x)]3 The Attempt at a Solution Find f'(5) for f(x)=g(h(x)) g'(h(x))*h'(x) g'(3)*-2 But I don't know where to go from there because I'm not given g'(3). Find f'(5) for [g(x)]3 I was thinking...

A 20 kg monkey holds on to a rope that passes over a frictionless pulley and is attached to a 20 kg bunch of bananas. The monkey starts to climb the rope to get the bananas. a. as the money climbs, do the bananas move up, down, or remain at rest? b. as the money climbs does the distance...

Homework Statement I am trying to write a short speech about angular momentum - aimed at kids leaving school and going on to university. I have started with a brief description of linear momentum, definition of vector, and them the fact that linear momentum is analogous to angular momentum and...

I'm currently studying mathematics at the undergraduate level and am required to conduct the following survey. I apologize if 'Career Guidance' is not the correct section for this, but it seemed the likeliest fit to me. Any responses at all would be greatly appreciated. 1.Please state your...

Hi, I have a short question about Nakahara's treatment about Laplacian's: page 294, section 7.9.5, equation (7.188). He calculates the Laplacion \Delta = dd^{\dagger} + d^{\dagger}d for a scalar function f. Every step is clear to me, except one; at the fourth line there is a factor of...

Assuming that all other conditions are the same, is a short person more stable than a tall person? Is the centre of gravity lower for a short person?

Take a laser source with small bandwidth centered around the average frequency (or wavelength) With an hypothetical external modulator that can switch as fast as we want, ca we make a pulse that is spatially shorter than 1 wavelength? If not? Why? What would that entail? Clearly the number...

Im learning math and physics on my own and I have had some problems when it comes to remembering how to do topics about math and physics. Currently I am trying to make more summaries, and a list of math and physics topics in order to remember more about them. Do you guys have any advice or...

Would somebody be kind enough to explain what exactly is meant when discussing short- or long-distance contributions/effects to branching ratio calculations?

http://www.cbc.ca/story/world/national/2006/05/26/short-prison.html?ref=rss Like Thompson, I am 5'1". I don't applaud the ruling. This is almost comical though. Prison is a danger to him, what about the child?

Hello All, I have short edge margin condition of 1.36D on one of the part.Actually 3 parts of aluminum are joined together by bolts and one part has short edge margin. All the parts have sufficient bearing strength.So if I understand right bearing failure occurs before...

I am looking for a suitable text for a short course that will be taught over a 16 week period. Students will take this nation-wide to compete for cash prizes and a college scholarship. Each year the subject matter is different and this year, it will be nuclear physics and chemistry. I am...

I can see the lack of input is frustrating, i too am so frustrated about the lack of testable results, but that is of no concern, so long as there exists a way forward, what is the way we should go?

If a full grown man in America is only five feet one inch tall, how much do you think his extremely short stature will affect his life? In what ways will being five feet one inch tall affect his life? Do you think that extremely short stature constitutes a significant hardship for men 5'2" and...

Hey, Well the summer is coming up, and as usual I do not have a lot planned really, other than a few days in Switzerland, and my sporting commitments. I am located in the UK, and I am looking for a short course that can be done online in Physics (I would have completed my AS levels). I do...

I've managed to calculate the viscosity of glycerol to be about 1.9 P. Google says it's supposed to be 1.5. Could I say that evaporated water has caused the glycerol to become more viscous than it should be? (It could just be a thicker glycerol but I'm just looking things to blab on about)...

Homework Statement Pb(NO3)2(aq) + H2SO4(aq) → PbSO3(s) + HNO3(aq) Pb + (NO3)2(aq) + H2 + SO4(aq) → PbSO3(s) + H + NO3(aq) The Attempt at a Solution So far I've done that, and now I'm stuck I see h2 and h can I cross out both or do i have to balance right now? My teacher said you can...

[SOLVED] Short optics question Shiny lawn spheres placed on pedestals are convex mirrors. One such sphere has a diameter of 42 cm. A 13 cm robin sits in a tree 2.1 m from the sphere. (a) Where is the image of the robin? in cm b) How long is the robin's image? in cm1/f=1/do+1/di hi/ho=-di/do Ok...

Homework Statement this is a 2 marks question a hole is drilled through a piece of steel what happens to the diameter of the hole as the steel is heated Homework Equations The Attempt at a Solution i guess the diameter of the hole decreases as both the outer as well as...

hi everyone, I am having a tough time convincing myself about the virtual short concept in opamps, As i understand from texts, on the application of a voltage on one of the input terminals of opamp, the voltage at the other input terminal is also forced to match the voltage on the first...

What is there about a particular protocol that defines its range of use? Is there such definition? i.e. 802.11 is used for short range high bandwidth, GSM/EGPRS for long range cellular communications and bluetooth for even shorter range communication on PANs. Is it possible for 802.11 to be...

What happens to gravity when something is very very dense but not a black hole? Do parts of it still attract each other as in less dense objects, ie according to the same inverse square law?

I have a few questions concerning opamps. First what is the big deal about infinite common mode rejection? It seems to me by looking at the open-loop gain equation A(V2 – V1) = V0 it is obvious that when V2 = V1 the output is zero (common mode rejection). This may be where I am confused …...

A Boeing 777 crashed yesterday at Heathrow apparently due to engine failure http://uk.reuters.com/article/domesticNews/idUKHO86894720080119?pageNumber=1&virtualBrandChannel=0 In the event of catastrophic engine failure wouldn't it be normal for Boeing to issue instructions for safety checks...

I notice consistently in the aftermarket exhaust world that in the majority of cases, when a longtube is placed on an engine the low to mid-range power picks up. This is also with the same size diameter primaries but different lengths. So I am comparing: Long tube: 30" primary tubes...

Homework Statement Hi, This isn't so much an actual problem, just more of a general question. Can anyone give me a layman's explanation of what a short circuit is and how a circuit breaker deals with that? Or, can anyone refer me to any sources that can? I have taken high school physics...

Is there any Short circuit protection diagram designed for power supplies which the current doesn't drop below 1A? Can you show me any?

Hey guys having a bit of problem with my year 1 essay. Would really appreciate any help :) What are the main sources of gamma ray bursts both short and long duration? I know some are from supernovae but where do others come from?

This is a little bit of a weird one. The question asks me to prove that [\hat{L}^2,\hat{L}_z ] is equal to zero. I know what to do with it and how commutators work, and I know that L2 = Lx2 + Ly2 + Lz2 (where the 2 means squared) and I have expressions for Lx2, Ly2 and Lz2, but I was just...

I am looking for a way to calculate the power spectrum of short signals of variable duration (between 200 and 500 ms). Standard methods seem wildly inaccurate. Are there any tricks for short segments? Thanks anyone for a response.

The figure below shows a worker poling a boat-a very efficient mode of transportation-across a shallow lake. He pushes parallel to the length of the light pole, exerting on the bottom of the lake a force of 225 N. Assume the pole lies in the vertical plane containing the boat's keel. At one...

What kind of short term and long term effects does DMT have on the brain?

Hi I was Just hoping to ask a short question about improper integrals ... when there are two limits in the integral: the 1st limit is divergent but the second limit is indeterminate... can it be automatically divergent? or do you need to evaluate first the second limit using LHR? so that...

Homework Statement Two particles move along an x axis. Position of particle 1 is x = 6t^2 + 3t + 2. The acceleration of particle 2 is given by a = -8t and at t=0, its velocity is 20 m/s. When the velocities of the particles match, what is their velocity? Homework Equations The...

Is there a limit to the possible amplification of Short Wave radio transmission and/or reception? A friend of mine wants to build a massive amplifier / transmitter. If a limit does exist what is the physical law used to explain it?

What does it mean when an integral sign has a short horizontal line drawn on it?

In battery, after finishing of its construction and positive & negative electrode creation, why we will need an external electrical lead (for example copper wires) for transmission of energy between two poles? Why no short circuit occurs between positive and negative electrodes through...

Let A and B be real invertible n x n matrices so that B = (AT)-1. Show that Bm = (I - B1A1T)(AmT)+, where B1 = [b1, ..., bm], Bm = [bm+1, ..., bn], A1 = [a1, ..., am], Am = [am+1, ..., an]. Any pointers on how one would go about proving the above? I'm fresh out of ideas. I'm not...

hello to all at PF! As I understand that this is an international forum, I would like to post my group's survey here to gain an international perspective! It's about the self-service concept. Thanks for all your efforts! Have a nice day!

I saw farmhouse magazine on chuck phallahnuik's (no clue how his name is spelled; dude who wrote fight club) website and figured I'd submit a story. They accepted it which is pretty cool :smile: My story's "white clouds," is very short, I hope you like it if you read it but if you don't that's...

This isn't really homework, but close enough. I suppose this is quite simple, but my head's all tangled up for today. Anyways, Given the real symmetric matrix LTL = UDUT, find L. I suppose L = +- D1/2UT, and it's clear this choice of L satisfies the given equation. But can it be proven that...

I don't know where else to ask something like this, but a friend of mine had her period and lasted a day and a half.. and is worried that she could be pregnant... but that's not possible if her eggs dropped because she started her period right?

Hello All, I'm designing a driver board to control some MOSFETs. I have some mic4427 MOSFET drivers to drive the gates into avalanche mode but the function generators I am using to trigger the chips only put out 50% duty cycle square waves. I'm working in a wide frequency range from 1 kHz to...

Hi all! This is a neat forum; wish I'd found it sooner... I'm writing a short scifi story, and am having trouble understanding time dilation, which happens to be an integral part of the story. Anyway, here's my question: Its common scifi staple where starfarers travel at close to the speed...

Can some1 tell me r there any short term courses available on aerodynamics or can anybody refer me a good book...