Water Definition and 1000 Threads

Many of the commercial and larger restaurant ice makers require that water temp pumped in for making ice needs to be 45F or higher. Anybody know why? Seemed like the colder the better, this side of freezing, everything would run more efficiently. I'm guessing it's cause however it's piped...

can cold air become water in a vacuum cylinder?

Homework Statement I want a detailed understanding of the temperature drop of a boiler when water is lost from a leak. I have a temperature recording of a leak that lasted for an hour and caused the temperature to drop from 170oC to 150oC when 2.55m3 of water was lost. I have tried using steam...

Water heater is set at 130 degree f freezer is 5 degrees f. Is it possible for a thermoelectric generator to collect energy from these placed side by side? Would the extra energy used by the heater and freezer due to the presence of the generator cancel out and then some any energy that could...

Whilst I was thinking of hydrogen combustion jet engines. I thought of a little idea... What if you could create thrust with water vapor the same way you could with the exhaust gas of a jet engine. (NOTE: I have no experience in engineering and I only have a mild interest in it). If this is...

From small generators attached to the gutters of your house to large ones in the storm sewers, is it efficient enough to make the effort?

Is it possible to dissolve diamonds with water?

Homework Statement Consider the same person at three locations. A: scuba diving underwater, B: standing on the beach, and C: standing on a mountain. Using <, >, =, make statements connecting the magnitude of their respective weights, i.e. ##W_A < W_B## Homework Equations Gravitational...

The dielectric constant of water is 80, however its refractive index is 1 ·33 invalidating the expression n*n=ε. why?

Homework Statement A pump, operating at 10 W, is used to raise the pressure of a stream of water at 2.5 mol/s from 1 bar to 2 bar. At steady state, if the water temperature should remain constant at 25oC, how much heat exchange between the pump and its surroundings is required? Note that 1 bar...

Hello, I have a question for you guys and gals. I am working on a Desalination project and am ironing out questions about efficiency. What would be the most efficient temperature to evaporate water? 50, 100, 110 degrees? Does it make a difference, or is the energy required to evaporate a fixed...

I've been wondering how I can find the pressure water exerts on a sphere it's in. As for cyllinders and pyramids, and prisms - the thing is extremely easy - you just take the one formula and put in numbers. What about a situation when we have a sphere whose radius is R, and it's half full with...

Hi, In an enclosed system - of say Methane & water - in which the water column is sufficiently large to have significant pressure and some modest temperature difference due to gravity and geothermal effects, how would one calculate / predict the changing methane concentration (or partial...

I'm trying to figure out how to best filter some liquids. A 5 gal bucket is filled with some filter medium (say sand on top 1/2 and fine charcoal on bottom 1/2). The liquid is slowly added at the top and gravity is used and vacuum may be used at some point with a complete seal along the bottom...

I heard that you can not survive a fall into water at a height of 250 feet or higher. I have also heard that the reason for this is it acts like concrete at the speed you would be traveling. My example scenario is kinda odd but goes like this. You are a paratrooper. You have just jumped out of...

I have a 8mm diameter glass tube willed with water that have a bulge outward above the top. I know that the preasure inside the bulge is higher than the outside (not postive as to why, probably due to it being in a liquid compare to the atmophere) the question is: 1. how do I calculate the...

Hi, I'm trying to do some figuring on vapor pressures. If one were to take two plates heated to 220F and press water between them in a press that exerts 100psi, what would the resulting vapor pressure of the water be? Now, what temperature would you heat the plates to if you were using a press...

Homework Statement Given a copper calorimeter that has a mass of 446 grams containing 95 grams of ice at 0.0°C. If 35 grams of steam at 100.0°C and 1.00 atm pressure is added to the can, what is the final temperature of the can and its contents? At the final temperature, how many kilograms are...

Homework Statement Homework EquationsThe Attempt at a Solution [/B] I'm confused with this question... first off isn't heat being removed from the product side since the Kw value is on the product side? If I assume heat is being removed from the product side, wouldn't the reaction shift to...

Hi all, I have a little problem while reading Feynman lecture note volume 2, chapter 40, section 40-3. In that section Mr Feynman talked about Bernoulli equation and a example of a filled water container. In high school we learned that if we drill a hole near bottom of container, we can get...

Homework Statement In the year 2004 the USA produced 1787 TWh of electrical energy in conventional thermal plants and 476 TWh in nuclear plants. Assuming 30% efficiency for nuclear plants and 40% for conventional thermal plants, determine the (annual) volume of cooling water required to cool...

Homework Statement Find the group velocity for a shallow water wave: ##\nu = \sqrt{\frac{2\pi\gamma}{\rho\lambda^3}}## Homework Equations Phase velocity: ##v_p = \nu\lambda## group velocity: ##v_g = \frac{d\omega}{dk}## ##k=\frac{2\pi}{\lambda}## ##\omega = 2\pi \nu##The Attempt at a Solution...

Good afternoon Wizards, (there are some really smart people here!) I have wired up my 1 hp water pump with #12-2 wire w/ground on 220 volts right at 400 feet. It registers the correct voltage and amperage at the pump. According to the wiring chart that came with the pump, I think I'm at the...

I have been on a project for awhile now and it has to do with production of bio ethanol production from biomass,and also how to add water in ratio 60:40. i.e ethanol will be 60% while water will be 40% without separating. I have tried to mix water with ethanol in this ratio but it keeps...

Might sound really stupid, but will it be more economical if instead of wall, a WIDE trench filled with water from adjoining ocean and river is allowed to flow in. With both the ends of the trench connected to the ocean, we can allow water to flow in during high tides, and flown out during low...

$\tiny{9.3.15}$ 4000 A tank contains 200 gal of fresh water. A solution containing 2 lb/gal of soluble lawn fertilizer runs into the tank at the rate of 1 gal/min, and the mixture is pumped out of the tank at the rate of 5 gal/min. Find the maximum amount of fertilizer in the tank and the time...

Homework Statement Water is initially at P = 1 bar and T = 20°C. 100kg of water is pumped to a higher pressure at which P = 10 bar and T = 25°C. Find ΔU and ΔH Homework Equations H = m*h du = c*dT dh = c*dT + v*dP The Attempt at a Solution So far I have looked in my table and found that at P...

Homework Statement Assuming that an OWC device is floating/moored in monochromatic waves. When there isn't air pressure distribution inside (atmospheric condition) the device behaves as an undambed body (with the oscillating chamber open to the atmosphere). When there is air pressure...

What is the process? And can/cannot it filter out?

Homework Statement We wish to heat water from 10 °C to 50 °C using vapor at 180 °C and 1.5 bar of pressure. How much cold water do we need to mix with every Kg of vapor to obtain the result? Homework Equations I am not sure. I think the problem is related with exergy and energy balance The...

So for the past two months I've been trying to get a gallon of water to chill to about 40-50 degrees in temp. in about 10-20 minutes. I wanted to use two TEC's(Thermal Electric coolers) attached to some heat sinks with fans expelling the heat. This would also be underneath the water/reservoir...

Hello all, I'm a Mechanical engineer with no prior experience in designing flow systems. I'm struggling with a hydraulic system that I have to design. the number of unknowns is large. but maybe by dividing the system to small sections, a solution can be found. I attached a schematic drawing...

Not really sure what's happening here, did a short search online to see if anyone else has documented this before. (If it's not clear from the photo, there seems to be a air bubble trapped right under the stream) It sustained itself for a couple minutes, took a short video of it too before it...

Homework Statement Here's the velocity profile of the water across the depth . I don't understand why The max velocity occur at the top surface[/B]Homework EquationsThe Attempt at a Solution Is it because the friction on the top surface of water only comes from the below , whereas for the...

Does anyone know how Hyman Rickover decided to prioritize pressurized light water reactor technology in the 1940s when there were so many technologies to choose from?

A big part of water on Earth come from comets at the very early ages of Earth so I suppose that the comets has same age as the Earth. The Earth and other objects come from a waste after creation of the Sun. The Sun come from cloud of hydrogen and helium mostly. It is star of 3rd-generation so I...

Homework Statement A hemispherical dome filled with water, radius 2 m and weight 30 tons, can be lifted by giving it a constant angular velocity around its vertical line of symmetry. The dome has a hole on the top. Decide the minimum angular velocity. My answer is 2.91 rad/s . The correct...

When we put an empty capillary tube in a water container, the water goes up a little bit by itself until the surface tension (ST) force is equal to its weight .This shows that unlike friction, this ST force acts individually . So if we take out the tube out of the container, and drain a little...

Clever idea behind this. Its basically a still. Only a small amount of water is heated at once, yielding 88% efficiency sunlight to evaporated water.

Homework Statement My problem includes answers from previous problems that are to be used as data in this problem so I will state the previous problems and the answers but not their solutions because I have solved them and they are pretty clear to me. So, I will be only posting the solution to...

Hi, I need some help to verify whether this is possible or not. I am working on a project that still in early phase of development. The idea is to create a water filter system to in a barrel as rolling it. Basically the barrel will contain 4 panels placed inside the barrel creating a shape of...

Homework Statement An office worker uses an immersion heater to warm 250 g of water in a light, covered, insulated cup from 20 degrees C to 100 degrees C in 4 minutes. The heater is Nichrome resistance wire connected to 120V power supply. Assume wire is at 100 degree C during 4 minute time...

I was cleaning up the kitchen, and there was a large pot that had been filled with water to soak in the sink. A rectangular nylon pot scrubber was hanging over the side of the pot, about 2/3 in the pot and 1/3 hanging out. As I ran the tap, the pot filled up and overflowed, but even after the...

I am trying to make my own alkaline water using baking soda and distilled water. First I measure out 0.018 moles of baking soda as follows (0.25 tsp)(1ml/.202 tst)(1.2 grams NaHCO3/ml)(1 mole NHCO3/1 gram NaHCO3) = .018 moles NaHCo3 I measure out 0.236 liters of distilled water i.e. 1 cup. The...

According to the first law of thermodynamics, dQ = dU + dW and you can find dU = nCvdT If this is the case then when water at 100°C vaporizes to steam at 100°C shouldn't the change in internal energy be zero because it is dependent on temperature change?

Homework Statement There is a cyllindrical glass (r=0.05 m) full of water. It is rotating around its vertical geometric axis with 3 turns per second. How many centimetres higher is water at the rim than in the centre of the glass . Water rotates together with the glass. Homework Equations...

< Mentor Note -- thread moved to HH from the technical math forums, so no HH Template is shown >[/color] I've encountered 2 problems in a row that involve lifting water out of tanks and finding the work needed. I am getting the incorrect answer. w = ⌠ab pgA(y)D(y)dy here is one of the...

Homework Statement Hello, i have the following assignment due for monday and i have truly no idea how to tackle it, i have already tried it many times but all my results have been wrong. the problem is as follows. inside a sealed container is an amount of water: mass=90.26 kg; pressure 9.1842...

I want to keep a small space (oh, say, about the size of a chest humidor - call it 2 cubic feet) humid to a level of about 70% to 80%. I don't feel like using the whole humidity technology that you have to fill all the time, so I've just stuck a gallon bucket of water in there. I was wondering...

hi all ran across an odd statement--about water: "Alkame has broken down the hydrogen bonds, reducing the waters molecular cluster size and increasing the residual of electrons ..." what does this mean?can we make fuel/hydrogen? increased electrons?power? another form of...