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Homework Statement Hello! I don't usually ask for help on homework, but I am really stuck and my physics teacher has no clue what she is doing. She doesn't really understand the material. Here is the question: There are two carotid arteries that feed blood to the brain, one on each side of the...

Homework Statement The number of 2 uF, 400 V capacitors is needed to obtain a capacitor value of 1.5 uF rated for 1600 V is..... Homework Equations The Attempt at a Solution equating the energy on both sides, 1/2*2*400^2*n=1/2*1.5*1600*1600, n=12, here n = number of capacitors...

Why isn't the dark matter just randomly distributed? How does it know where to go? Why does the amount of dark matter increase the further away from the galaxy's center?

Hello. I am graduating next year (i'll be 19) in Sweden, and I am interested in studying at a university in the US, but I am afraid I will not get accepted. My grades are sort of good (although I am not satisfied at all). The maximum score is 22.5 which is equal to straight A's, and I will...

Dear all, I would to like to ask do anyone have any idea on how to increase the COP and SCP(Specific Cooling Power) of a silica gel absorption chiller? COP= Heat removed by evaporator/ Heat supplied to system( normally is the hot water supplied to the absorption bed) SCP= heat removed at...

If we boost voltage from 3.7v to 12v, is this will affect on watt we consumption from the battery or make your battery discharge faster?

Does this mean if I had a rubber band and weighed it, then stretched and weighed it while being stretched out, that it would weigh more at that time? Since at that time it has stored energy, which equates to mass?

Homework Statement Hello! I need to find a local linear increase in the field of the lens. I have Listing of Field Curvature Data. It contains vectors of - Y height, Tan Shift, Sag Shift, Real Height, Ref. Height, Distortion. I can not understand how these data get what I need. Homework...

I am designing DC-DC capacitive based charge controller for charging 12V battery using variable dc power supply and then with solar panel as input sources.This charge controller topology is step up boost converter so by using PWM variable duty cycle technique I made its output fixed at 12V but...

Homework Statement How does a dielectric increase maximum electric field strength? From the two cases where a dielectric is inserted into a charged capacitor after it is disconnected and after it is remained connected it seems that E will either decrease or stay the same. But I read in...

Homework Statement Students must create an irrigation system that takes water from a reservoir 80 cm deep to a wave pool across the room. A perfectly leveled horizontal tube with constant circumference takes water from the bottom of the reservoir to the wave pool. Why would adding more...

I want to pump energy into a chemical species to increase its reaction cross section with another. Typically these species react upon collision when their relative kinetic energy exceeds the activation energy. I want to find a way to increase the reaction rate for interactions at slower...

Hey guys, I'm having trouble with this problem set I'm working on at the moment. I'd appreciate some help with this question: This thread is only for question one. Please ignore number two. So I used the quotient rule to differentiate, giving me: f'(x) = [2x(x-2)-2(x^2)]/(x-2)^3...

Hey guys, Need some more help again. I'll keep it brief. This thread is only for question one. Please ignore 2ab. I started off by computing f'(x) via the product rule and calculating the zeros, at which point I got: x= 1/√ 5 and x=√(3) However, I'm at a loss as to what I should do...

How to calculate the raise in temperature of air when it's pressurized by a piston type air pump from atmospheric pressure to 3 bar(gauge pressure) ?

Homework Statement Imagine that the temperature of 255 g of aluminum sitting in the sum increases from 278 K to 294 K. By how much has its entropy increased? Homework Equations Q=mcΔT ΔS=Q/T The Attempt at a Solution Q=(255 g)(.90 J/gK)(294 K -278 K) Q=3672 J ΔS=Q/T...

Is it possible that I keep the typical working torque but increase the rpm by raising my voltage to my motor? I have this motor and control board: http://uk.rs-online.com/web/p/stepper-motors/3514631/ http://uk.rs-online.com/web/p/stepper-drives-indexers/2407920/?origin=PSF_421243|acc...

Hi Im trying to increase the length of a movement of a rope so when one rope is pulled the other rope movement is increased x 2 (it is attached across). So far i have tried gears whice has somewhat worked but it increases the force as well. Is there any other way to achieve this amplification...

I need help finding the temperature rise of a liquid (specifically diesel) due to a pressure increase. The system contains a pump at 500 hp and runs at 524 gpm. The inlet temperature is 75 F and the pressure is 150 psi. The exit pressure is about 1155 psi. I have the specific gravity as 0.841...

Dear Sir, I am trying to understand that whether a Pump who is flowing a High Temperature Fluid (Therminol) will be feasible with a Gear Box. The Gear Box will be used to increase the pump speed from 3000 rpm to 3600 rpm. The reason behind increasing the speed is high Pump TDH and as per...

Homework Statement Uranium has two common isotopes with atomic masses of 238 and 235. One way to separate these isotopes is to combine the uranium with fluorine to make uranium hexafluoride gas, UF6, and then to let it effuse through a small hole. The natural abundance of the 235U isotope is...

I have been learning a lot about STEM focused schools (sixth form and high school) recently because I have got an offer from a Mathematics specific school myself, in London. I noticed that there are very few in the UK at all. I know that it is a very small country in comparison to the USA but I...

If a positive charge A moves towards another stationary positive charge B then the A's electric potential energy increases. But shouldn't the electric potential energy of B also increase as it is also in a way moving towards the A inside the A's electric field? So shouldn't the total...

Boiling point elevation depends on how many ions dissociate in the solution. Typically CaCl2 is a good substance to use but it has a pretty high molar mass... I'm wondering what the best substance to use to increase the boiling point of water? Thanks!

Homework Statement A metal rod of length L at temperature of 0°C is not uniformly heated such that the temperature is given by the distance x along its length measured from one end when: T(x) = T_0 \sin (\pi x/L) Accordingly, points at x = 0 and x = L are also zero temperature, whereas at x...

Here is my theory: - The measurement of an observable by an observer is a thermodynamically irreversible process. All thermodynamically irreversible processes increase total system entropy. - Landauer's principle (which was experimentally shown in 2012) says that the minimum amount of energy...

I was curious as to why when a star discontinues fusion its gravitational pull grows stronger? My guess - When a star is actively burning, the fusion is somehow warping space and/or suppressing the gravitational pull. When the star stop fusion, this force is no longer present and the star feels...

Homework Statement Find increase in pulse duration for 10 fs laser pulse going through 20 mm of fused silica (\phi^{(2)})=361.626 fs^{2} for 10 mm of fused silica)Homework Equations The Attempt at a Solution I have no idea where to begin with this. Can anyone give me some equations or send me...

Homework Statement Is boiling of egg accompanied by an increase in entropy? The Attempt at a Solution I guess entropy decreases because as the egg boils, the stuff inside it gets hardened and changes into a solid mass. So the disorderliness decreases and the entropy should decrease. But...

Hello everyone. I'm having 5v,100 mA current in the rectified output. I used a 7805 ic to regulate the voltage and a pair of capacitor as filters. And my question is i want 500 mA current in the output keeping 5v constant. Is that possible? Any circuit to increase the current? Thank you hope...

I need to calculate the increase in drag due to an airbrake, however the formula includes "semi span". I'm unsure if this is simply wing span/2 or is it the length of a wing in which case it would be (wing span - fuse width)/2. Any help would be good.

Homework Statement So in one of our practice problems it states that as we increase the doping concentrations, the result will be a decrease in mobility. However, I thought that when you increase doping concentrations, there will be a higher concentration of carriers available for...

Homework Statement Rubbing your hands together warms them by converting work into thermal energy. If a woman rubs her hands back and forth for a total of 10 rubs a distance of 7.50 cm each and with a frictional force averaging 45.0 N, what is the temperature increase? The mass of tissue...

Flywheel? I don't know much about magnets, but if i used magnets on the out side of a flywheel and the inside of the flywheel caseing which repel each other effectively crushing the flywheel to oppose centrifugal forces. Would this creat greater resistance on the rotation of the flywheel? Thanks

Homework Statement An inflatable membrane is filled with an ideal gas at a pressure of 0.3 bar gauge. The gas is at 40 deg C and the volume of the membrane is 100m^3. The membrane is constrained on all sides and bottom, and a force of F acts on the top of the membrane. The material the...

Dear all, I would like to ask: Given a control volume (V1), at an initial temperature (T1), the pressure (P1) in the volume (V1) is decreased by sucking out air. The suction hole is then closed to achieve a state of P2 * V2 = n2 * R * T2 . What would happen to the temperature in the control...

hey. i need a help about a water tank. i want to increase the velocity of water at my home. my home use water tank to increase the velocity of water but its not enough for me. its that any way for me to increase the velocity of water without adjust the height of the water tank itself? thank

Hi people, I need help to this problemSomeone has suggested that the device shown in the figure below be used to improve the maximum force F against the spring, which has a spring constant of k. This is accomplished by changing the temperature of the liquid-vapor mixture in the container. You...

Homework Statement This is not a homework problem. Okay, it is -- but I have solved it correctly already, so the question is not there. I'm just not sure about a detail in one of many solutions. We have a hollow cylinder with a uniform mass distribution rolling down an incline with some...

As you can see, around Reynolds number of 5 105 the transition occurs for a smooth sphere. However, why is it that after this transition that the drag coefficient increases at turbulence?

Homework Statement using a climate sensitivity of 0.5K per watt per square meter, estimate how much of the .9 c global temperature increase since 1900 could be due to solar forcing who value is the range of .06 to .24 w/m2 Homework Equations The Attempt at a Solution .5 x .06 =...

Hello, I will try to be frank, as I am not sure if I can get the help I need in this forum. I am not an EE but dabble here and there (you'd probably call it hacking at a very crude level). Overview I have a new electronic dartboard which has a small speaker on it. The speaker announces...

And I mean the angle with the normal vector. Suppose you shine a laser through a prism at a large angle of incidence, and the prism has index of refraction 1.7. You get the angle of incidence high enough, and you get total internal reflection. Then you put a 1/4 wavelength layer of MgF, index...

I know what is lattice constant but it has been given that nano particles have reduced lattice constant due to huge fraction of atoms being in surface. How come the lattice constant of nano particles reduced due to high number of atoms present in surface? Why do the surface area, hardness...

Hello All, I work in the refrigeration industry, and I'm trying to put a hard number on a hypothetical situation. The situation is a lapse in SOP and liquid gets trapped in a line. For this hypothetical situation the line is 100% full. What would the increase in pressure be per degree? I...

I had an interesting idea for increasing the Specific Impulse and Thrust of a nuclear rocket engine; it's probably not practical - best case scenario 20% increase in exhaust velocity, with proportional increase in thrust, at the cost of 1.5x to 2x weight increase, and likely much lower - but I...

Homework Statement To assemble a uniformly charged sphere, assemble it like a snowball, layer by layer, each time bringing in an infinitesimal charge dq from far away and smearing it uniformly over the surface, thereby increasing the radius. How much work dW does it take to build up the radius...

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...

Alright.I am preparing for engineering entrance exams next year.Most of the standard questions of Classical mechanics requires you to imagine the whole scenario in 3D.Unless you are able to vizualize it,You can't solve the problem.I am able to vizualize 70-80% of the problems but my imagination...