Loss Definition and 793 Threads

Hey guys, I tried to figure this out and got a rough estimate but thought I’d ask the experts. I use the Sola SDU500 UPSs in our systems. A customer wants to know how long they will last if there is a power outage. I believe the power consumption for the entire system would be ~12Wh...

A sine wave source charge a capacitor through a diode. Is it more efficiency than a DC source charging a capacitor ? base on this https://www.physicsforums.com/attachment.php?attachmentid=17653&d=1235114409

Hi everyone. I am currently carrying out an experiment whereby I have a closed tank of water submerged in a larger tank. The water in the smaller box is heated and I am interested in the heat loss from the tank. I have done a rough theoretical calculation based on U values, where by I obtain...

Here is the problem: http://postimage.org/image/1jy6nol5w/ Method 1: Steps 1. Calculate V(T1)=12*10=120V, V(T2)=10*10=100V 2. Since V(3)=10V and I(3)=1A, P(T3)=10W 3. Since not otherwise stated, Assume transformers are perfect. 4. So P(T3)= P(T2) = 10W 5. known...

I've heard that losing weight does not decrease the number of fat cells your body contains. But does this number decrease if you maintain this lower weight over time? I'm thinking that over time, the fat cells die and are replaced at a lower rate.

Good day. just want to ask anyone about copper loss. How is it computed for example in a manufacturing plant or in a dept mall.Could anyone give an illustration/example? Also , is it true that copper loss can be reduced by using big wires?What if the wire is big enough? thank you. hope...

Why is there permanent muscle loss from space travel? Is this general muscle atrophy or specific to certain muscles (i.e., which muscles don't experience permanent atrophy and why)?

loss US Academic Competitiveness... hype? In my opinion all this hype about American students underperforming Chinese, Russian, & Korean students in math is overblown. Even if it is true it's not that big of a deal and the methodology used to come to these conclusions is flawed. In America...

Hi everyone! Im having a project and i need to estimate the return hight of a falling yoyo The yoyo is built of two 120cm radius and 2cm long cylinders connected by another one with a radius of 2.5cm and 30cm long. It is droped from the height of 30m with a rope that's 20m long. How can i...

We all know that Earth's core is relatively hotter than the Earth's surface. And with this temperature gradient, there must me a loss of heat from the Earth's core to the surface and then to atmosphere and outer space by convection and radiation. So, how much time it would require for the...

Hi, I'm new, so this may be on the wrong board, but I thought it was more particle-energy-stuff than astro. So to the point - dark matter is non interacting with EM fields, and can't emit photons. Yes? OK, given this, how could dark matter lose energy. For example, when normal matter is...

I have an experiment in which I have two solenoids where one induces an EMF in the other. I then introduce copper plates between the two coils and measure the decrease in induced EMF in the second solenoid. How could I calculate the power loss due to eddy currents induced in one of the copper...

Heat Exchanger! I have steam flowing past two pipes which have cold water flowing in them. I want to find out how much heat is lost from the cold water and thus the final temperature of the cold water when it leaves the pipe. I am doing this as an experiment and before I start I want to know...

A room contains 25 kg of air at 100KPa and 10 degree C. The room has a 250-W refrigerator (the refrigerator consumes 250 W of electricity when running) and 1-KW electric resistance heater. During a cold winter day, it is observed that both the refrigerator and the resistance heater are running...

Homework Statement http://img710.imageshack.us/i/2631001.jpg/ #29 Homework Equations p=I^2R P=IV The Attempt at a Solution well, the answer is D, but i don't see why the length matters? can anyone find out the equation for this problem? i thought it was B) cable B because it has...

Homework Statement What equation do i use to calculate the power loss due to eddy currents? I can't find an equation anywhere online.

http://hyperphysics.phy-astr.gsu.edu/hbase/inecol.html When a block in motion(M1) collides with a a stationary object (M2) in a perfectly inelastic collision, the fraction of KE final/KE initial can be modeled as M2/M1+M2. My question is if M2 has to be stationary for this equation to...

Hi, Not sure if this is the correct sub-forum or not. Perhaps, general math is better. Anyways.. In the following, a simple reference covering what I am after would be very helpful. Let's say you have a 4x4 grid of cells each cell contains either a 1 or 0. Let's say it is this...

Hi every body This question came to my mind when I was looking at a Home Heating System. The system is a closed loop. In this closed loop of pipe hot water is flowing. I know the temperature of the pipe in the beginning and at the end of the pipe. I also know the flow rate of water in the...

Hi, is physically correct to say "loss of temperature"? Doesn't the "loss" relate just to "heat"?

Tom's thread "Why I'm REALLY disappointed..." continues to get increasingly thought-provoking and informative. I summarized some recent discussion here: https://www.physicsforums.com/showthread.php?p=3219363#post3219363 I had some reaction to recent posts by Suprised and Tom that I will put in...

in the movie i was watching that is set in space, some of the characters get frozen while exposed to the vacuum of space without being properly insulated. Now i am wondering is my understanding of heat energy incorrect. I thought heat would be taken from the body by every atom that interacts...

hey guys, I am currently trying to implement a voltage divider to step down from 9V DC for a digital output. I am using two resistors, 3.3M ohm & 2.7M ohm in series. When I measure the voltage across both of them using a multimeter I get 9.5V Across the 3.3M ohm resistor I get 2.2V...

Dear all, Hi I am involved in a project and I want to model an induction machine with two three phase stators. The frequency and number of poles of the two set are different. How can I write a formula for the core loss of the stator? There are two sinusoidal waveforms at stator. Can I use...

If a condenser were to lose its supply of cooling water and no trips were activated how could you calculate when the vacuum would be lost? i.e. calculate the length of time before no more steam could be accepted by the condenser.

I am researching the best shape for a hose clamp to provide a consistent and predictable friction loss in the 1 to 2 psi range. The hose diameter will be either 3 or 4 inches and the water flow will typically be in the range of 10 to 50 gpm. The idea is that the hose clamp can be finely...

Homework Statement A 15.0 kg block is dragged over a rough, horizontal surface by a 74.9 N force acting at 17.6 degrees above the horizontal. The block is displaced 4.91 m, and the coefficient of kinetic friction is 0.266. Find the work done by the 74.9 N force = 351 J Find the work done...

Is there a formula for calculating heat loss due to wind (not wind chill temperature)?

Homework Statement In my electromagnetics book, in the section that talks about loss tangents, the equation for average power dissipation per unit volume is P=(1/2)*J*E (W/m^3). What does the coefficient of 1/2 come from? Earlier in the book, it gave the differential power dissipation dP=...

The intensity (W/m^2) of an electromagnetic wave from an ordinary antenna decreases with the square of the distance from the emitter (in the far field.) Is the same true for a laser beam?

In acute blood loss both RBC and fluid is lost, so why doesn't haemotocrit stay normal. I know compensatory mechanism would increase the fluid, eg kidney. But red blood cell prodcution would take few weeks. Is that the reason haemotocrit decreases? Thanks :smile:

Hi, ok so everytime I think that I have understood the concept of Energy transmission, losses and voltage drop, I get even more confused about things. I have searched several threads on this forum and the physics forum but failed to find anything that directly answers my query. So I...

Maybe this question has already been asked, anyway, here it goes. The universe is expanding and according to relativity, the radiation is redshifted, meaning there is a loss of energy. If energy is conserved, where does that loss of energy go?

This problem of loss of taste started for me about 2 years ago but now it has reach the point that it is very annoying. I get no taste or the taste is somehow distorted when i eat foods that have fats like meat, cheese. When i eat foods like sweets that contain sugar the taste seems to be ok...

I can't seem to get any of the answers for this - please help! Two stars of equal mass M orbit a common centre. The radius of the orbit of each star is R. Assume that each of the stars has a mass equal to 1.5 solar masses (solar mass=2x10^30kg) and that the initial separation of the stars is...

So I am having this problem at work where a 150kW induction motor is being used as an induction generator. There is a capacitor bank in parallel to the induction generator which is primarily for PFC(the reactive power requirement of the generator is fed by the grid). Assume the induction...

Homework Statement Calculate wall loss rate in BTUs per hour. For a 10 ft by 10 ft room with an 8 ft ceiling, with all surfaces insulated to R19 as recommended by the U.S. Department of Energy, with inside temperature 68°F and outside temperature 28°F: heat loss = \frac{Q}{t} = \frac{(Area)...

Not particually a paradox, just liked the word play. Anyway... The definition of a redox reaction is a reaction with both reduction and oxidation. As we know, oxidation is loss, reduction is gain of electrons. So redox is a reaction with both loss and gain of reaction. Does it follow that...

I have been trying to establish what the heat loss and exit temp (in deg C) for 100ml of water traveling down a pipe located externally to a building and subjected to -10degC air temperatures will be if: The pipe has an internal diameter of 19mm and a length of 3m. 100ml of water with...

Homework Statement A pipe of radius R is maintained at temperature T. It is covered in insulation and the insulated pipe has radius r. Assume all surfaces lose heat through Newton's law of cooling \vec{J} = \vec{h} \Delta T, where the magnitude h is assumed to be constant. Show that...

Question: How much heat is lost in one hour through a 15 cm x 3.7m x 6.1m concrete floor if the inside temperature is 22 degrees c and the ground temperature is 13 degrees c? some info: thermal conductivity of concrete=1.1 change in temperature=8 Relative Equations: kAchangeT/L...

Does radiation from electrical devices such as computers, phones, WiFi etc.. have an effect on hair loss? Can't really find a lot of articles on the net about it.

I've been thinking of developing a program which predicts the motion of two colloding billard balls, I wanted to encorperate some energy loss in the collision since its not an elastic collision. My question is which root would be the valid or real result of a collision. Imagine two billard...

Hi there... My question is that when nucleon's loses energy (such as in fusion),does that affect their size as well? do they also shrink or grow by losing or gaining energy?

How can I determine the heat loss of person from sweating when given the weight of the person and the weight of the amount of sweat that was evaporated throughout the day?

Hi I am studying this topic at the moment and came across this question but cannot solve it. Any help would be much appreciated. Heat is transferred from a resevoir at 1200C to a second resevoir at 350C at a rate of 500 KJ/s. Calculate the rate at which work potential is destroyed during...

Homework Statement We recently did a lab in my physics class where we looked at the conservation of energy of a ball on a roller-coaster track. We got the data as seen in the picture below http://tinypic.com/r/168zx2s/7 the question now is why is there negative energy loss, is this...

Homework Statement I'm analysing a mass spectrum I've been given for a molecule with the molecular formula of C9H10O2. The structure iv deduced is a Benzene ring with COOC2H5 substituent. so its... Benzene-C(=O)-O-C2H5 I'm working out the fragments shown on the mass spec. Those...

For an analysis of a robot component: a Spur gear drive/train. How can I account for friction losses? I can calculate the torque, with neglecting friction. And what about the change in energy? I know power = torque*angular velocity

Homework Statement Suppose that you own a poorly insulated small house, with outside walls l = 0.25m thick, total outer wall plus roof surface area 210m^2 (about 1992 ft^2) and your walls have a thermal conductivity of 1.3 W/m·K (limestone). Calculate how much power your air conditioner will...