Loss Definition and 793 Threads

Hello i have a noobquestion: does a polymer ion battery lose capacity faster when charged and discharged at the same time??

hi.I would like to know something about the IC engine.I just read an article.It said that 30% efficiency is gone through conduction of heat by the cylinder wall.If it is reason for one of the efficiency loss why can't we build an cylinder coated with a material that is non conduction.So only...

I have a centrifugal water pump that I would like to protect during the winter months. The pipes can be drained, but there are some locations that are at risk for retaining trapped water, which can be problematic whenever we actually need to run the pumps. I am proposing that a heated...

So I'm trying to figure out where a heat tracing program is getting some numbers. What I'm trying to figure out is how the program calculates the internal temperature of the tracing lines. What I know is the k value of the insulation 0.0215 watts per metre*degree I know the temperature...

Bill was a fellow Australian and prolific comet hunter and discoverer Quoted from the Ice In Space site He will be truly missed in the astronomical community :( Regards Dave

Homework Statement How would I go about finding the energy loss of a Pendulum from top (Ep) to Bot (Ek) Mass= 2.0kg Length= 0.38m height= 0.05091m theta= 30° 2. The attempt at a solution I know that we could find Ep by going mgh (2.0kg)(9.81m/s)(0.05091m)=1.0J of Ep But how...

Is there a way to reinstall win7 without the disk and without losing all of my data? The only back up I have is a bit old and I can't get my external hard drive to connect. I have a rather bad virus and I can't seem to get rid of it, so I am thinking its best just to reinstall windows.

I am aware that when charged particles accelerate or decelerate, the particle will emit a certain amount of radiation. But since a charged particle will accelerate any time it goes around a bend in a circuit, wouldn't it radiate some energy when it goes around the bend? I thought that giving...

Hi, I have a very oily skin especially in the face and hair. I think the oil causes acnes or something called foliculit. Foliculits and oil started at the end of the secondary schools which corresponds to puberty. I used a tablet it was good for me. It dried my skin against oil but it dried...

Sea level appears destined to rise at least 4ft. Anyone have data on how this will affect the world's coastlines? West Antarctic Glacier Loss Appears Unstoppable http://www.jpl.nasa.gov/news/news.php?release=2014-148 The 'Unstable' West Antarctic Ice Sheet: A Primer...

Hi there, I am dealing with a pipe that is surrounded by air and trying to calculate the temperature drop. The inlet temperature is 1273K and the ambient air is 293K. In my quest to do so I have calculated the overall heat transfer coefficient to be around 10 W/m2K, which I believe for a gas...

Greetings. I am not sure how to approximate a MOSFET's switching energy from datasheet parameters. I have stumbled upon a few ways, but in all cases I've found it is pretty rare to find a datasheet with all the correct parameters. Here are some ways I've found: 1) Eon and Eoff are listed...

Homework Statement A vacuum flask of radius r and length l consists of two concentric cylinders separated by a narrow gap containing a gas at pressure 10^-2 Nm^-2. The liquid in the flask is at 60 degrees Celcius and the air outside is at 20 degrees celcius. Estimate the rate of heat loss by...

8. All KE is lost when: (a) two bodies of equal mass collide, (b) two bodies of opposite initial velocity collide, (c) two bodies of equal mass and opposite initial velocity collide, (d) never. None of these make sense to me. (a) Billard balls have elastic collisions. (b) Billard balls...

Homework Statement I'm struggling to understand question 1.C How do I incorporate Tw and later eliminate this? Homework Equations -k*A*(ΔT/ΔX) The Attempt at a Solution For 1.a I used this equation: -k*A*((Tinside-Toutside)/thickness wall) I thought to put T inside first as...

Hi, I need clarification on the difference in head loss for turbulent flow and laminar flow. I understand how the head loss due to friction is different for the two regimes. For friction head loss, the friction factor is 64/Re for laminar flow, and a more complex formula for turbulent flow. I...

In wikipedia, it said for optical fiber, a loss that takes place at discontinuities of refractive index, especially at an air-glass interface such as a fiber endface. At those interfaces, a fraction of the optical signal is reflected back toward the source. But what I learned in tranmission...

Power loss doubt: power loss = I^2 R Power loss = V^2 / R But the 2 equations are contradictory ,,, from the first equation , we can say " MORE THE RESISTANCE MORE THE POWER LOSS" from the second equation ,,, it is the other way round... Why does this happen? ( usually the 1st equation is used...

I'm revising attenuation and power loss logarithmic equations. The exam formula I'm given is attenuation = 10 log (I1/I2) I'm trying to confirm what each I stands for. Some of the examples I'm looking at seen to give input/output power, some seem to reverse it. Which is right? What do they...

So I was thinking what are the differences between ionization and radiation energy loss for particles through a material? Its weird cause I see the similarities but not seeing the differences...A friend brought it up in class today lol

Shift workers beware: Sleep loss may cause brain damage, new research says http://www.cnn.com/2014/03/19/health/sleep-loss-brain-damage/index.html?hpt=hp_t2

Homework Statement A (smooth) rope of length L and mass m is placed above a hole in a table. One end of the rope falls through the hole, pulling steadily on the remainder of the rope. Find the velocity of the rope as a function of the distance to the end of the rope, x. Ignore friction of the...

Hi, In a similar vein to the weight of flying birds in a sealed van etc. Let's say a woman weighs exactly 10 stones 7 pounds on the morning she is due to give birth. She starts to dilate etc. and heads to hospital. She gives birth to a beautiful baby girl weighing in at exactly 7 pounds...

Homework Statement I was asked to compare the energy loss of a system of two boxes moving towards each other, colliding elastically and in-elastically in two different situations that are not influenced by friction. There are no springs attached to either massThe Attempt at a Solution I...

Homework Statement The pendulum of a grandfather clock activates an escapement mechanism every time it passes through the vertical. The escapement is under tension (provided by a hanging weight) and gives the pendulum a small impulse a distance l from the pivot. The energy transferred by...

Hi, I am introducing myself to logic circuits and I want to build a network of logic gates (CMOS) that have push buttons as inputs and LEDs as ouputs. At most there are 4 gates between a button and a LED. However, at the inputs of the 4th gate, which is a AND gate, I measure 4 V and 4 V, but...

Hi Qoutation: "Kinetic theory of matter: All matter is made up of atoms and molecules that are constantly moving. When heat is added to a substance, the molecules and atoms vibrate faster. As atoms vibrate faster, the space between atoms increases. The motion and spacing of the particles...

Hello everyone I still don't understand crystalloids 1) Let's say someone lost 100 ml of blood due to accident. If you are giving crystalloid therapy, why do you have to infuse 3 times the amount. What I think is when you give crystalloids IV, they go into extravascular and...

Homework Statement A factory receives 120kW of power from a power station 20km away via transmission lines. If the resistance in the power lines is 0.5Ω/km, what is the power loss in the lines if the electricity is transmitted at 100kV (Approximate to a simple DC circuit). Homework Equations V...

I'm trying to write a very, very simple heat flow simulation program. The idea is an environment space is a grid, with each grid space identical in respect to all other grid spaces (I'm calling a grid space an "element") except temperature. So, they are physically the same except temperature...

Is the same torque required at any freq in order to overcome these losses?

Hey Guys, How do I work out Transmission loses and input impedance for coaxial cable? I’ve been given this website to use http://fermi.la.asu.edu/w9cf/tran/ I do have the characteristic impedance of 75Ω and frequency and I am asked to work the attenuation in dB/100ft and “input...

Good day. I was wondering what the extent of resistance/voltage drop occurs over junctions that are made off movable parts and brushes. Electrical trains tend to get the voltage from brushes so it can't be too great, also brushed motors. In my case I was planning to run an electric brushless...

Homework Statement A merry-go-round is sitting in a playground. It is free to rotate, but is currently stationary. You can model it as a uniform disk of mass 220 kg and radius 100 cm (consider the metal poles to have a negligible mass compared to the merry-go-round). The poles near the edge...

One of the most popular mass loss equations of a star, developed by D. Reimers, is given by: dM/dt = -(4x10^-13) * η(L/(gR)) solar masses per year Where η is a free parameter close to unity and L, g, and R are the luminosity of the star, surface gravity of the star, and the radius of the star...

When following solutions like this link: http://physics.about.com/od/physicsmtop/g/PerfectlyInelasticCollision.htm I understand that energy is lost, but it doesn't necessarily show that this is MAXIMUM energy loss, just that there is energy lost. How would you go about proving that more energy...

Homework Statement A small power plant produces a voltage of 6.0 kV and 150 A. The voltage is stepped up to 240 kV by the transformer before it is transmitted to a substation. The resistance of the transmission line between the power plants and the substation is 75 Ohms. What percentage...

Sodastream sells a device that will charge a 1 liter bottle of water with CO2 gas so you can drink fizzy beverages. I always use 40F cold water from the fridge to fill the bottle, and seal it tightly, but I find that after only 1-2 days 90% of the fizz is gone, a much shorter life than fizz...

Homework Statement Homework Equations m1v1i+m2v2i=m1v1f+m2v2fThe Attempt at a Solution I tried doing MV=m1v1f+m2v2f I know that the sum of the momentum of the two parts is equal to the the momentum of the the full shell. Since I have two unknowns, I used the conservation of energy. I set used...

Maxwell-Wagner polarization is generally described in literature as the polarization of interfaces, such as grain boundaries, with an applied electric field. In the Wikipedia article (http://en.wikipedia.org/wiki/Maxwell–Wagner–Sillars_polarization), it's mentioned that "the charges are often...

I'm having to design a screw pump and I'm a bit confused about things, I've never really seen a screw pump before. I've decided upon a twin screw - screw pump and my first question is why do most examples have an outlet at a higher level than the input, surely that just leads to a pressure loss...

Hi, I have been trying to understand eddy current loss in transformer cores but seem to have run into a bit of a misunderstanding with one of the books I have read, and I was wondering if someone could just clarify if I have got this all right. starting with the beginning, if the magnetic...

How many watts would you need to keep a 64oz bottle of water at 40 degrees when the temperature surrounding the bottle is 10 degrees (that's assuming you don't take into account surface area) ? How many btus if you took into account the surface area of a 64oz soda bottle ? What I did...

Homework Statement Calculate the insertion loss for the network in the diagram? Homework Equations 20log(N)dB N = R0 + R1 / R0 - R1 The Attempt at a Solution N = R0 + R1 / R0 - R1 N = 141.42 + 100 / 141.42 - 100 N = 241.42 / 41.42...

Dumb question, but something I don't get. I see this expressed in many basic examples of what voltage is. You have 1 object that has too many electrons and 1 object has too little. The potential difference between them is what is expressed as/in volts. If you connect a conductive wire...

Homework Statement If only conductive heat loss was significant for a house, then by what percentage would you lower the heat loss if the temperature was reduced inside from 70°F to 68°F, when the outside temperature is 26°F? (Hint: Try using a ratio.) Homework Equations N/A, use a...

I am building a mathematical model of a piston engine which calculates the pressure and temperature of the cylinder gas every 1° of crank angle. I'm having some difficulty with the heat transfer to and from the cylinder wall (to when the Tg > Tw and from when Tg < Tw). I found the heat...

I'm struggling to understand the implications and origins of the 2nd law. Entropy is such a slippery subject. Wikipedia has many many definitions of entropy. I've been studying Professor Susskind physics lectures, so I'm most interested in his favorite definition: that information is...

Howdy everyone, I'm sorry if this is in the wrong forum, but since I believe it is mostly a thermodynamics problem I think this is the right arena. My questions stems from trying to insulate a bank of batteries in cold weather. I am trying to determine the proper material and design...

http://www.theguardian.com/film/2013/sep/05/jack-nicholson-retires-memory-loss Sound like it's possibly more serious than an aging memory. It surprises me because The Departed was just on TV a few nights ago and I happened to see it for the first time. This was released in 2006, just 6 years...