New answers tagged

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The ship drops the anchor which, in virtue of the stock (rebatable or collapsible arm near the top, perpendicular to the plane of the flukes)(flukes = triangular "nails" which should grab the bottom if sandy or muddy, or hook to stony bottoms) will, with the subsequent pulling of the vessel, dig one (or both) of the flukes into sandy/muddy bottom. But this ...


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Actually. the velocity can be determined as follows. V = sq. root of 2gh where: V = velocity in ft./sec. g = acceleration const. 32.2 ft per sec per sec. And h = head in feet of liquid. h = P * 2.31/SG where: P = pressure in psi. SG = liquid specific gravity. With the above information you can now calculate F.


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Using Bernoulli's equation and the momentum conservation equation, we can show that water flowing out of a pipe with cross-section $A$ at speed $v$ exerts a force $F$ on a wall (at 90 degrees), acc.: $$F=\rho Av^2$$ With $\rho$ the density of the water. But your specification of "8" pipe with 500psi stream of water exiting it and hitting a wall at 90 ...


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I think it depends on what your friend means by "with respect to the water" When I hear that I think spatially. sample constants: you travel 1 meter per stroke, 1 second per stroke, water traveling 1 meter per second. When swimming downstream you'll cover 2 meters with respect to the ground in 1 second (yay for triathlons that are downstream). However, ...


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Yes. It's is not so much the water is the beach sand reflecting light back to you like a parabolic mirror. The droplets of water on your skin can form more surface area to catch light creating a magnifying effect focusing light on your skin as well. The random texture in the beach sand will also give you even tan. Most sand is white in color even if not the ...


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No, there is not because, contrary to your last sentence: The amount of water and the container itself I am not concerned with, strictly some sort of equation I could use to get a measurement of time. the boiling time is not a well defined quantity unless you take these things into account carefully. To calculate the rate of temperature rise you need ...


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Is there actually any evidence that being in water increases your risk of getting sunburn? I suspect that this inference confuses correlation with cause. On brilliant sunny days you are more likely to strip off and get in the pool or go to the beach to cool down. If swimming or diving you are unlikely to wear a sunhat. More of your skin (especially the ...


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Yes. It's is not so much the water is the beach sand reflecting light back to you like a parabolic mirror. The droplets of water on your skin can form more surface area to catch light creating a magnifying effect focusing light on your skin as well. The random texture in the beach sand will also give you even tan. Most sand is white in color even if not the ...


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heres the whole way these water bags work you soak them in water first then fill them and hang them up the water inside keeps the bag wet and the outside surface moisture evaporates cooling the water inside the water is not ice cold only cool but much better than what it would be with no cooling effect at all


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This can happen when water is heated under pressure. If the pressure is sufficient to keep the water liquid at a temperature well above its usual boiling point, and then the pressure is abruptly removed, the water will "flash" into steam all at once, causing what's known as a boiling liquid expanding vapor explosion.


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From the original assumptions: So far, my understanding of water evaporating is the following: The higher the temperature, the higher the vapor pressure, therefore the faster water vaporizes. The rate of water boiling, assuming a constant boiling temperature, is dependent on the rate of heat transfer to the water, not the vapor pressure. At sea level, ...


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If water in some volume $V$ becomes gas (the attraction between water molecules is switched off instantly), then the pressure of this gas will be enormous. This is how explosive works.


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The answers boils down to yes, the larger the rate of of heat (assuming you can transfer it at any rate you want), the larger the vaporization rate. The rate of change in internal energy at constant volume is $U=U_0+\dot Q\Delta t$, where $\Delta U$ is the total internal energy necessary to change the phase, and $\dot Q$ is the rate of heat transfer. Thus $\...


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My answer is based on our everyday experience. The simple answer is no. Suppose you have a hot pan, now put a drop of water over it and you will see that it will sustain for a while. This is because the steam makes a insulating layer between the pan and water drop. This phenomena is always present which (may not be the only reason) is one of the reasons ...


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Huh, people? :-) He says the main tank is closed! That means it can be pressurised, and the pressure will ofc push out water, depending on pump efficiency. Nothing else needed than a valve that hinders the water from flowing back to the open reservoir when the pump is off. In the pic below a self-adjusting system. - If there is too little water in the ...


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Another suggestion: close valve 1 and 2 and turn on pump to make 'fountain' effect. Close valve 1 and open valve 2 and turn on pump to transfer water from reservoir to tank. Close valve 2, open valve 1 and turn off pump, to transfer water from tank to reservoir.


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The answer is no, simply because the pressure on the check valve on the side of the open pond must be greater than that within the main tank before the valve can open and let water flow from the open pond and the main tank. This will only happen if either: The open pond's water level is higher than that of the open tank; as drawn, the system will simply ...


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@phillip_0008 Pretty sure this one would work! Basically, no need for valve 3. And wouldn't be able to access valve 2. So split pump inlet between bottom of tank and bottom of reservoir, directly outlet to fountain. Water coming out of fountain sits in reservoir until it gets sucked back in thru pump. makes sense in my mind but let me know if you see ...


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How about: open valve 2 to transfer water from the reseroir to the tank. Close valve 2 to create the 'fountain' feature. Open valve 3 to transfer water from tank to reservoir.


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The water level in the pond must be the same as in the tank, so: :-)


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It is an optical illusion that uses stroboscopic light. It is the same principle that allows you to see still pictures into a movie. For instance, when you see the drops floating still, the drop is not the same, the light frequency is synchronized with that of the the falling drops, so that every time the light is on it shows you the image of a different ...


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Water vapour can be said to be one of the the most important contributor to the greenhouse effect. To estimate its potentiality is a bit complex exercise as the absorption ranges of wavelengths in the infra-red region overlaps for different green house gases. In some of these overlap regions , the atmosphere already absorbs 100% of radiation, ...


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This is a more general answer. Atoms and molecules are quantum mechanical entities. This means that the "shape" of atoms depends on the solution of quantum mechanical equations, which give probabilities for locating in space the electrons that are bound to the nucleus of the atom with the electric potential provided by the protons of the nucleus. The ...


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The water molecule is neutral on overall basis, i.e: the water molecule as a whole has no net charge. The water molecule is not linear rather it has a bent shape with two hydrogens on the same side. This happens because of the lone-pair-bond-pair repulsions. The oxygen has is a more electronegative element than hydrogen, i.e: oxygen has high electron-...


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Water can not bear normal loads as well as oil. Water is bound to escape from high pressure bearings to lower presser places in an open lubrication loop leaving bear contacts. Water can create bubbles around cavities and corners and break the laminar flow which will compromise the separation of moving parts. Water will react chemically with surfaces. There ...


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I think the question is really pertinent. If you heat the liquid without any impurity and in a flask with very smooth walls, kept at higher pressure until the temperature is just below the boiling point at that pressure and you slowly start to reduce the pressure, you will find that the water is not started to boil, this state is known as super heated state. ...


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@tbf is right; lubrication, and tribology in general, is complicated. That's why there is that high effort to understand it and to design advanced materials. There are several phenomena that cause the friction force exist and the ones you have neglected causes that oils are superior to water in most industral applications. In dry sliding we can identify ...


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The parallel plate situation that you describe is not the typical condition encountered in practical lubrication operations. In addition to facilitating the surfaces sliding over one another, the lubricated bearing must also support a normal load. To do this, the gap between the surfaces varies with location along the bearing. For example, in a journal ...


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Why Oil is Slippery Explaining why oil is slippery requires a look at its chemical properties. First, oil is non-polar, which means it does not have a positive or negative charge. Some molecules, like water, have a “charge distribution,” which means the molecule acts almost like a battery, part of it has a positive charge and part of it has a ...


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A good lubricant tends to effectively minimize direct contact among components of any device that need it Keeping this in mind, viscosity is not the only factor involved. Grind a graphite pencil lead, and it makes a mighty fine lubricant. It might be that in the case of water placed between two surfaces, a water droplet which was supposed to act as an ...


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Your derivation is composed of correct statements and indeed, if something is known to act as a lubricant, we want the viscosity to be as low as possible because the friction will be reduced in this way. For example, honey is a bad lubricant because it's too viscous. However, your derivation isn't the whole story. The second condition is that the two ...


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Water is the people's most popular liquid but it is also one that differs from almost all other liquids in some almost qualitative ways. The most important reason why water is considered an "improper liquid" is that its density is higher than the density of its solid phase, the ice. For "proper liquids", it's the other way around – the solid phase is ...


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I only find the expression "proper liquid" (in this context) in works from the 19th century. An obvious reason would be the highly non-linear expansion curve (note that the picture below doesn't show that curve itself, but rather its derivative). For mercury, the secant volumetric expansion coefficient varies very little, from $0.18165*10^{-3}$ at 0°C to $0....


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Your calculation of the heats up to the melting point are correct and useful. If we devide that heat by the heat capacity of the air and the mass of the air, we obtain 22.308K. This is the amount by which the air's temperature has dropped by the time the ice is completely molten and at 0°C. Now we can continue to calculate the final temperature by the ...


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The density of water (and other fluids) depends both on the pressure and the temperature. A graph for water is here: You may see that at 1 bar (1 atmosphere), the density is highest around 4 °C. That's the conditions where the density reaches the nice 1,000 kilograms per cubic meter. Water contracts when it gets warmer than that, but also when it gets ...


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Sunlight, made up of a mixture of all colors, scatters when it passes between materials, each with a different refractive index, in this case water and air. The water in the river only meets the air at one surface, but the droplets in the air/water mixture contains millions of surfaces. This combination scatters the light more so it appears white overall,...



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