Sign Definition and 579 Threads

Homework Statement If you are hanging a sign from the ceiling with two wires, each with a safe working load of 20N. The hooks at the top of the sign are 2.0 meters apart while the hooks in the ceiling are 4.0 meters apart. A) If the sign weighs 30N what is the minimum angle to the horizontal...

What does it mean when an op amp has only a minus sign in its symbol? Is the positive terminal at ground, or is it at some arbitrary voltage?

Homework Statement Hans stands at the of the Grand Canyon and yodels down to the bottom. He hears his yodel echo back from the canyon floor 5.20s later. Assume that the speed of sound in air is 340.0m/s. How deep is the canyon at this location? I made a chart. Velocity Original = 340...

Homework Statement 4. In Fig. 23-28, a butterfly net is in a uniform electric field of magnitude {E = 3.0} mN/C. The rim, a circle of radius a = 11 cm, is aligned perpendicular to the field. The net contains no net charge. Find the electric flux through the netting...

I'm working on this hanging sign problem: A sign hangs precariously from your prof's office door. Calculate the magnitude of the tension in string 1, if θ1 = 27.42°, θ2 = 67.35°, and the mass of the sign is 9.9 kg. I was wondering if I could put 9.9*9.8 as a leg in the middle of the...

Hi all. Say, I have an alegebric function, e.g. f(y;a)=y^4+b*y^3+c*y^2+d*y+e, where the coefficients b,c,d and e are all depends on a single parameter, a. What I want to do is to check what is the condition of a for the function f(y;a) to change its sign between 0 and 1+a, do you have any...

Please help! This is urgent! Homework Statement 1) A typical car's brakes can create a maximum acceleration of less than 5 m/s^2 . How close can you get to a stop sign before you start braking? Homework Equations no idea at all since there isn't even enough information given to solve...

What does an equal sign with a straight line down the middle of it mean?

Hello: I need help determining if I and V assignments follow the passive sign convention. Here is the image of the circuit: http://img178.imageshack.us/img178/9572/pic1xu2.gif I know that in order for it to follow PSC the current I needs to flow towards +V. I'm not sure if that is...

Latex - how to get non-italic UK "pound" sign I'm using MikTex. When I do \usepackage{times} and then use \pound or \textsterling in non-maths mode, I get the italic version of the "pound" symbol from the Times Roman font. I want a non-italic pound symbol. I also get this message in...

Homework Statement How come it is said that attractive forces such as gravitational force have negative sign? And how come the sign is ignored in the case of gravitational force? And also, how come gravitational potential energy carries a negative sign? Is it because the displacement of the...

I have a hard time trying to derive the equation in 6.4 . This is what I've done, and as you will see I have a sign difference compared to his. http://scitation.aip.org/getpdf/servlet/GetPDFServlet?filetype=pdf&id=PRVDAQ000070000001015012000001&idtype=cvips&prog=normal Starting with page 8...

Would obviously synthetic particles traveling through space be a choice to broadcast the presence of life? Likewise, say we detected an unnaturally large cross section of an otherwise rare particle impinging upon Earth; might that vestige be a purposeful indication of extraterrestrial civilization?

at the bottom of a post? i mean your userid is just to the left of the post? is it so that if someone murders you and tries to infiltrate our ranks we'll know? maybe it's because some of you write such long posts that by the time one reads the whole thing scrolling up is counterproductive? bob

hi. 1. Why does the sign of the metric have to be (+,-,-,-) or (-,+,+,+)? meaning why does the sign in front of the time part of the metric have to be different than the signs in front of the spatial part of the metric? is there a good answer for this question other than it gives the right...

To clear up the confusion of signs to use for mirrors and lenses. Would this be a correct way of memorizing the signs? For the equation: 1/s_o+1/s_i=1/f Mirrors: Concave: Since light actually converges at the focal point, it's positive. Any image that is on the same side as the focal point...

i am studing physics and i Sign up for this courses and I think it is to much: 1st year: Introduction to physics I Introduction to physics II Mathematic (matrixes) Mathematic (Calculus & Analysis) Mathematic (matrixes & Vectors) Mathematic (probability theory) Introduction to chemistry...

the material is over coulombs law, and i am having a rough time understanding the business of the sign's of the charges and the direction of the charge at the same time. here is a problem from the text.: Two charges are located on the x-axis with q1 = 2.3 x 10^-8 C at the orgin, and with q2...

Homework Statement a.) What is the lowest number represented by a 12-bit machine using Sign Magnitude? b.) What is the largest? c.) What decimal number does the bit pattern "101001010010" represent?Homework Equations For a and b: Signed integer ranges for N bits (I don't know if this is...

Homework Statement This is ralated to completely monotone functions. if a function and its successive derivative changes sign then what does this mean? Homework Equations The Attempt at a Solution

minus sign in "forces in space" problem. Homework Statement see picture for problem. Homework Equations please see a picture (one is of problem, the other contains the relevant formula). The Attempt at a Solution I was able to solve the whole thing, then looked at the solution...

Hi, Let L be an inductance, then you find the following formula in textbooks (high school level): U_ind = - L dI/dt When you actually do calculations for circuits, you see that the minus sign is wrong. So why do they put it there?

I guess this is more of an anthropological post. Is there any pattern to which sign convention people prefer? Or is it just a matter of which you were exposed to first?

Electrodes in cells usually have a sign of either + or - My textbook talks about the + as because the electrode is positively charged and - when negatively charged. But is that correct? The electrodes are meant to be conductors and shouldn't be charged at any time. When they do, the ions...

Hi, I have posted this doubt in other forums and people don't know the answer. (sorry if my English is not very good!) Let's see: to obtain the operator for the magnetic moment component of a particle, we have to apply a few factors to the spin operator, and one of them, the so-called...

This is my (error full?) understanding from my readings: 1. positive current flowing into a positive terminal of let's say a rechargeable battery is power being absorbed by the battery...so positive watts 2. negative current flowing into a positive terminal encounters the higher electrical...

Homework Statement http://online.physics.uiuc.edu/cgi/courses/shell/phys102/fall06/prep2a.pl?practice/exam1/fa06 Homework Equations W =F*D The Attempt at a Solution I have it solved, now i thought - would be if i put work into the thing to move it but looking at it since both of...

If you have two blocks connected over a pulley, and are using the torque on the pulley to calculate the acceleration, then you should disregard the sign of the torque, always treating it as positive, no matter which direction it rotates? Is this right? Thanks, Dorothy

Sometimes the following symbols are used instead of an equal sign. I think the single one ~ means "is proportional to". One of the other ones means "is approximately". Which one is it? I'm guessing the second one because LaTex calls it approx. When are the others used? \begin{array}{l}...

I have been having a really rough time on my 3 homework problems tonight...I don't really understand vectors, so any help would be appreciated! Sorry about the no LaTeX, I don't know how to do the vector sign:confused: Anyway... 1.Given the Vectors U=2i(hat)-3j(hat)= <2,-3> and...

I know Kirchoff's 2nd law but when applying to an electrical circuit i am bit confused :confused: with taking correct signs for emf,product of resistor & currect etc. Anyone please help me to solve problems related with Kirchoff's 2nd law in an easy way.

Hi. Okay, this has been driving me crazy. When combining two given waves into a standing wave equation, how do you know which sign to put in front of the amplitude? All the examples I've been finding seem to contradict each other. Here are three examples from my textbook: 1. Incoming Wave...

Hi there, We are about to use that sigma sign in chemistry we have however not got told about it in math. SO therefore I am asking you if you could give me a brief introduction to it and how to use it and etc.

Can someone point me to a reliable source (textbook, website) that teaches this technique? It seems like no course at my university covers this technique even though it is quite useful for solving particular integrals!

Sir, I am confused on what sign conventions to follow. I reffered 5 or six books which says that focal length of convex mirror is positive and focal length of concave mirror is negative. But in Resinick & halliday,wikipedia and many other websites it is given the opposite. Please help me!

In terms of the thermodynamic identity: dU = {\tau}d{\sigma} - pdV the term for the work done on the system (-pdV) must be positive if there is a compression, in which case dV would be negative, correct? If one wanted to write the identity in terms of the work done *by* the system, you...

http://news.bbc.co.uk/2/hi/uk_news/4981720.stm It has long been suspected that this sort of thing may account for some UFO reports - perhaps a good number of the more interesting cases. Of course it remains to be shown that such a phenomenon really does exist that can affect humans to the...

I believe it was world something or other day in the US yesterday so with that in mind:- What would it take for the US to sign an agreed protocol to help combat climate change? I read recently that the US has a population of 298 million roughly yet produces more CO2 than Europe population 450...

Hi, I'll get right away to the point. I'm determining damping coefficients from motion sensor traces of a damped oscillator. I have gone through the standard procedure of taking natural logs of the sine wave peaks and drawing graphs etc, however what puzzles me is that the SIGN of the damping...

need to hand in an assingment in an hour. would appreciate help on this : "Does the light emitted by a neon sign constitute a continuous spectrum or only a few colors? Defend your answer" thank you

\int \frac{1+e^x}{1-e^x}dx = \int \frac{dx}{1-e^x} + \int \frac{e^x}{1-e^x}dx The second integral can be done by the substitution u = 1-e^x du = -e^x dx So the second integral becomes: \int \frac{du}{u} = \ln|u|+C In the first integral, you can use the substituion: w = e^x...

for 10011101 and 11001100 ,what is the decimal value in sign magnitude format (8bits) ?? pls help

Hello everyone, when I'm doing these problems i always make sure i put a negative inside the sin(x) function, then just later take it out like cos(2t)+sin(-2t) = cos(2t)-sin(2t); Because sin is an odd function. But my professor says f it and never does, for instance here is my work, i came out...

Businesses just keep tightening their budgets more and more. Last year the division I work for flew everyone to Las Vegas to celebrate the annual branch kickoff. This year, we're driving down the block to a cheesy strip mall type convention center for TWO hours to celebrate. I'll bet if I'm...

http://news.yahoo.com/s/ap/20051201/ap_on_re_ca/canada_climate_change Those countries are missing out on the moolah. :smile:

Ok, I am doing my calculus homework, but sometimes I get a negative in the wrong place... Here is an example: The solution I got for the derivative attached is on the numerator: 5e^x(9e^x)-5e^x(4+9e^x) In the solution, the negative sign is on the other side?? I don't get it

I have always used a calculator to find the sin when the angle is given. But how would you figure this out if you didn't have a calculator

Hi So I am a little confused about the absolute value sign here. Is the derivative right: [x-1/|x-1|]e^x + |x-1|e^x But what do I do when I set this to zero? Do I get two expressions, one for x>1 and one for x<1 ? (thus removing the absolute value signs)

Q. The base of the freeway sign is attached to its foundation with four bolts.The four bolts must be able to resist the twisiting of the pole that is caused by the wind. Assume each bolt carries the same force. If the diameter of the bolt circle is 0.9m, calculate the horizontal (shear) force on...

Hello Im really confused on the signs for f, do and di in this equation.. Please tell me if I am correct.. but here is how i presently understand if For definition sake, the 'front' of a mirror is where you would normally stand to look in a mirror, and the 'front' of a lens (like a camera)...