Balance Definition and 461 Threads

Hi guys, so I'm having a little trouble completing my physics lab report here due to not being able to find many errors to discuss about. The experiment that I conducted makes use of a basic current balance: http://www.pasco.com/prodCatalog/SF/SF-8607_basic-current-balance/ As you all know...

Hi everyone. I'm confused with the balance of energy in this situation (I'm comparing the mechanical energy, initially, at rest, at a height = h, and then, at the end, at height = 0). It doesn't seem to be fine, maybe I missed something. I'd appreciate some help - Everything is in the .jpg...

Hey! :o At the cylinder of the picture there are static pressures from environment fluid of density $\rho$. If we neglect the atmospheric pressure, calculate how much force and how much torque is needed so that the cylinder balance. In my notes there is the solution, but I haven't really...

If I'll shove a bicycle down the road, without even being on it, it will go on perfectly without crashing, until it will reach to a minimal speed and then crash. Why is that? why can't we balance an imobile bicycle? A lot say it has to do with the gyroscopic effect but my physics professor said...

Hello PF! I have some questions regarding the accumulation term for the energy balance on a variable volume system. Suppose we have a tank storing a liquid substance. The tank has a moving boundary at the top, which can expand unlimitedly. The system has a mass input \dot{m}_1 and mass output...

Homework Statement Pure iron sulfide (FeS2) is fed into an Herreshoff furnace at 25 °C. An 83% of excess air is also fed into the furnace at 25 °C. The solid product consists only of Fe2O3. The solid product reaches a temperature of 1832 °C, and the exhaust gases (8.7% SO2, 9.8% O2, 81.5% N2)...

Homework Statement A block of mass m= 10kg rests on a horizontal table. The coefficient of friction between the block and the table is 0.05. When hit by a bullet of mass 50 g moving with speed v, that gets embedded in it, the block moves and comes to stop after moving a distance of 2m on the...

Homework Statement A coil of fine copper wire has a resistance of 6.2 -Ω and a total mass is 14.4 g. What is the diameter d of the wire and what is its length L? (The density of copper is 8.96 g/cm3.) Hint Given: •Model the wire as a long cylinder of diameter d and length L. Write one...

Homework Statement A cylindrical tank, with a diameter Db, open to the atmosphere, is drained through an orifice in the bottom of the tank with a diameter Do. The speed of the fluid flowing through the orifice is given by v = \sqrt{2gh}, where h is the height of the liquid measured from the...

The General Energy balance equation is: ∑ENin - ∑ENout + Egen = Est (in rate form - don't know how to put the dot above) I know that Est is 0 when the system operates at Steady State Steady Flow (SSSF). I have 2 formulas for ΔE in "Q-W = ΔE" 1) ΔE = ΔU + ΔKE + ΔPE 2) ΔE = m[h2 - h1...

Hello PF! I have a simple question on energy balances. Suppose you have an isothermal reactor where you want to have an exothermic reaction happening at 450 °C. The simplified energy balance for the reactor is Q = ΔH. Supposing ΔH = -150 kcal, then Q = -150 kcal. Does this mean that, a) in order...

Homework Statement If we have a beta + deca: $$^{22}_{11}Na(3^+)\rightarrow ^{22}_{10}Ne(2^+)+ e^+ +\nu $$ with $t_{1/2}=2.6 years$, what is the energy balance at this decay, if you know that $^{22}_{10}Ne(2^+)$ is an excited state of $^{22}_{10}Ne$ with $1.25 MeV$ larger energy. Homework...

Hi, yesterday i saw this video on discovery channel. <link to video deleted> in the documentation it was said that this trick with the three hammers and three rulers doesn´t match with actual laws of physics! does anyone can give more information about this?

I'm interested in how much $ I've contributed to my Social Security and Medicare savings account over my lifetime. Where can I go to view the balance? Can someone provide with a URL to the government site that shows how much is in my lock box?

Homework Statement The problem is this: what is the optimum amount of dry ice inside the Styrofoam pack, if we want to received a frozen dough (temp.-18) after 3 days of transportation in temperature 20 C ? My calculations and data placed in the attached excel file, but I'm not sure if they...

Homework Statement A horizontal uniform bar of mass 260 kg and length L = 3.0 m is placed on two supports, labeled A and B, located as shown in the diagram. A block of mass 60 kg is placed on the right end of the bar. Find the normal forces FA and FB exerted on the bar by the supports. Enter...

Homework Statement A certain pyrite ore contains 85% of FeS2 and 15% of inerts. This ore is introduced into a roasting furnace with 20% excess air, in order to oxidize the FeS2 in the reaction: \textrm{FeS}_2 + \frac{11}{4}\textrm{O}_2 \rightarrow \frac{1}{2}\textrm{Fe}_2 \textrm{O}_3 +...

Two liquids, A and B, are mixed together. A is 5.00% solids, the rest water. B is 11.0% solids, the rest water. To the mixture is added 18.5 kg of bone-dry solids resulting in a mixture of 2 150 kg containing 8.25% solids. What were the original amounts of the liquids A and B?

Homework Statement if a potentiometer has driver cell and wire AB ,then an unknown emf (emf<driver cell) is balanced at some length L. does the balance point change if internal resistance of driver cell is changed? Homework Equations V= kl K= potential gradient The Attempt at a...

Homework Statement [/B] I don't understand what I'm doing wrong with this problem: An old club-ax consists of a symmetrical 8.3 kg stone attached to the end of a uniform 2.9 kg stick. The stick is 98 cm long, and the 18 cm long stone is drilled through its center and mounted on one end of the...

Hi all, I am an architect student in college and I am trying to calculate the reactions in the question in the follwing url ( https://www.flickr.com/photos/123626386@N07/16250310830/ ) I have attempted the question and got two values which can be seen in the following url...

Homework Statement Attached document Homework Equations m(flow)*(v1-v2)+P1A1-P2A2 The Attempt at a Solution I did a mass balance to plug into the momentum balance, but I am not getting the final equation correct.

Let's consider a simple roulette game, where one may either get red or black. Since the probabiblity P of an event A, P(A) is defined as the relative frequency at which the event occurs, if we get red , say 3 times in a row, it is very likely that the next random pick will be black. My question...

MODERATOR NOTE: THIS THREAD WAS ORIGINALLY POSTED SOMEWHERE ELSE, SO THERE IS NO TEMPLATE. Dear! I have a problem with one, complex exercise. I’ve divided it into three parts just to simplify finding the answer. So let’s start. The air is sucked from the atmosphere by a compressor. Atmospheric...

1. Homework Statement Establish the condition required to make the current through Ze in Figure 1 zero (i.e. For the voltage Vx to equal Vy). Homework EquationsThe Attempt at a Solution I'm not sure if I'm on the right line here, hopefully someone can point me in the right direction if it's...

Homework Statement A student performs a single replacement reaction by dipping a strip of copper metal, Cu(s), into an aqueous solution of silver nitrate, AgN03(aq), to produce silver, Ag(s). Write the balanced equation. Homework Equations The Attempt at a Solution The answer has...

Hi everybody. This is my first thread ever on this forum :S I'm in a first year physics class, and the other day we did a lab involving a c.c.c (current carrying conductor) and a magnet on a balance. The c.c.c was a wire which completed a circuit. One had a magnet assembly which was placed on...

I have been struggling to balance my study social life for a while now, when i study for instance i often overdo it doing like 5 hours after school this really accelerates my learning but leaves me feeling slightly depressed, stressed and overworked. However the opposite occurs when i try to...

< Mentor Note -- thread moved to HH from the technical physics forums, so no HH Template is shown >[/color] I am looking for a very simplistic and understandable explanation for how it works as I don't seem to find any place that explains it well... I am just doing A Level which is equivalent...

Hello, when doing mass and/or energy balances, how does one know when one should use a differential balance over a total balance? It would help when knowing how to approach a given problem.

Homework Statement We have a pendulum in thermal balance with the surroundings - no damping. We measure the speed of the pendulum. The accuracy of each speed measurement is known. How does the accuracy of the speed change, if we decide also measure the position of the pendulum with accuracy 10%...

Hello PF! I have a very short question. We're currently doing enthalpy balances for chemical reactions in our Thermo class. We are using the simple enthalpy balance equation: \Delta H_{\textrm{Reaction}}^0 = \sum \Delta H_{\textrm{Products}}^0 - \sum \Delta H_{\textrm{Reactants}}^0 My question...

Hello, I just began learning mass transfer, and I am trying to use analogies from heat transfer to help me solve problems. For example, if you have one dimensional heat transfer through a plane wall, I would start with a general energy balance. $$\frac {dE}{dt} = \dot Q_{x} - \dot Q_{x + \Delta...

Homework Statement when the balance point is achieved , there're no current passing thru , so Galvanometer should show 0 . Am i right... so there's no current passing thru the 20 ohm resistor . so my working is ( 8.1/120 )(40) = 2.7 V ... correct me if I'm wrong...Homework EquationsThe Attempt...

Hi all, I could use some assistance with the following problem. "The spring of a spring balance is 5.0in. long when there is no weight on the balance, and it is 9.6in. long with 8.0 lb hung from the balance. How much work is done stretching it from 5.0in to 12.2in?" So far, I know to take...

Homework Statement Write the balanced chemical reactions in ionic and neutral forms for: i) Enargite leaching by sodium bisulfide in basic solution to form chalcocite and thioarsenate. ii) Oxygen pressure oxidation of As2S5 in acid solution to form scorodite. Assume all sulfide sulfur forms...

Homework Statement Hi. I have convert the following equation (which is in ionic form) into neutral form: 4S2O32-+O2+2H2O=2S4O62-+4OH- The question tells me to use calcium as a counterion for all anions. Homework Equations N/A The Attempt at a Solution I basically just added calcium to the...

I am currently looking facing a problem concerning a spring slider system. The system consists of a electro engine that pulls on a spring with a constant velocity. The spring is attached to a block that sticks to the surface, but after a certain force is applied (by the spring) starts to slip...

I have an issue with this question: An aqueous solution containing 15% NaOH and 0.5% NaCl is concentrated at a rate of 100 kg/min in an evaporator. The concentrated solution is then mixed with 2000 kg of aqueous NaOH solution in a mixer. At the end of one hour a sample is collected from the...

Hi there, I want to know what is the best way to connect these devices to a 3 phase power supply outlet and minimise the unbalanced load as much as possible safely? I am only worried about the single phase appliances. What type of connection would you recommend? 3x Power Supply units Single...

In a late 1980s trade journal, I saw a full-page of polar balance diagrams for each major engine type. For each engine type (V6, V8, inline 6, inline 4, V12, etc) a circular polar chart was presented with overlaid color-coded graphs showing 1st, 2nd and 3rd order balance for 360 degrees of...

Hi there. I'm reading Gurtin's 'the mechanics and thermodynamics of continua', and working some exercises of his book. In the section 21: 'The first law: balance of energy', after the derivation of the balance equation, he uses an identity to rewrite the balance of energy. The balance of energy...

I have already balanced beam both side two same mass at same distance and it is pivot on its center of gravity...so torque is zero so no rotation possible by gravity on earth......so why beam always be horizontal to Earth surface...after give inclination to Earth surface.....potential energy not...

Hi there! My physics is not exactly strong (I am a games developer/designer). Basically I have a game idea where the player will jump between the floor and the ceiling. At any point the player will jump and be affected by the gravitational point of the ceiling and the floor at the same...

I have little to no experience with this area of physics, so don't assume I know certain things. A cone is spun (with the tip down) at a constant, not decreasing, RPM (Rotations per Minute). What is the minimum RPM for it to stay there without falling, and (if possible) the minimum RPM necessary...

I am working out of the 2010 lindeburg book which can be found here. The solution is in the book so I am actually looking for an explanation rather than a solutution. http://www.scribd.com/doc/113765067/FE-Review-Manual-Lindeburg-2010 this is chapter 10 pg 8 in the chapter, reviewing the...

Hey all! I think I have the problem within my grasp, just would like a second opinion to help me cross the finish line... Homework Statement Consider the following diagram of the bottle holder assembly (see attachment). The weight of the bottle is 11N, and the weight of the board is...

Hi I want to estimate divergence of water vapor flux in atmosphere with NCEP/NCAR data I have the equations for that and i want the algorithms to implement it for NCEP/NCAR data. I have a paper with algorithms for ECMWF data. Can i take this? or it required new algorithms for my data

Can someone please help balance these weights? I would say the bottom and second to bottom connect as I circled them so they are balanced, but it gets really confusing after this.

Hi, I'd really like to understand How a torsion balance works and exactly how You can use math to derive the Coulombs law. Is thre a good - realtively easy to understand - video or do someone have some good notes explaining exactly how it works? I'd really appreicate it.