# Tag Info

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The accepted answer is not complete. A projectile may travel very long distances underwater if it is supercavitating. A supercavitating object is a high speed submerged object that is designed to initiate a cavitation bubble at the nose which (either naturally or augmented with internally generated gas) extends past the aft end of the object, ...

2

Several things are happening here that may make the sensations of touching metal and touching water similar when they are at room temperature (~ 25 C), although the thermal conductivities are a couple of orders of magnitude different. The sensation of coldness comes from the loss of heat from the part of your body contacting the material. The rate of heat ...

1

The parts of your body that generate heat and that can sense temperature and the loss of heat are insulated from the environment by a layer of dead skin cells. The total thermal conductivity to the environment is the thermal conductivity of the materials that you touch in series with the thermal conductivity of this layer of skin. Since this layer has a ...

2

The simplest answer is that this has to do with symmetry. In the immediate vicinity of the droplet, the water is isotropic. Therefore there is no preferred direction. In more rigorous terms, the density-density correlation function for liquid water is rotationally and translationally invariant. Now, if one were to change the geometry of the problem in some ...

1

You can also see the exact same phenomenon when you see a bubble. Bubbles always occupy spherical spaces. This occurs due to the fact that a ripple expands in every direction at a constant rate so naturally the resultant shape the ripple encloses is a circle. This might also be related to the fact that for any given area, the smallest perimeter is bounded by ...

0

It is because stones dropped from a larger height have reached larger speeds when touching the water and larger speeds means more kinetic energy and momentum, and that means a larger explosion, and that means more water falling out of the cup. Every nonlinearity in some level is cancelled by another one at another level such that the relationship between ...

3

This has everything to do with entropy: when the temperature is higher, the benefit of having more water molecules in the air (giving rise to greater entropy) become energetically more favored. This is why water "dissolves better in air" at higher temperatures. Another way of looking at this (pure statistical thermodynamics): when water is cold, few ...

1

This phenomenon has nothing to do with the properties of the air, but the properties of the water in it. Hot air means hot water in the air. Cold air means cold water in the air. Cooling water causes it to condense. This is considering a constant volume.

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Just to add an explanation to sh37211's good empirical answer: the microwave transfers energy to the water at a constant rate. For a microwave rated 1,300 Watts and a typical 50% efficiency$^1$ that means a constant 650 Watts of heat energy delivered to the water. To calculate the change in temperature $(\Delta T)$ of a mass of material $(m)$ based on how ...

-4

ice is a crystal pure made up of water after frozen on a certain temperature,as it is lighter than water hence its density is less than water............this can be taken as in simple words

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Qualitative Reasoning As you anticipated, the shape of the velocity distribution (what you call local motion) does not depend on the position but is dictated by the Maxwell-Boltzmann distribution. To answer in short then: the average velocity of molecules does not vary as a function of distance from the container wall (here I am using "wall" as an idealized ...

3

I did some research and it seems that superhydrophobic coating can be used to decrease drag forces to a certain extent because the coating repels the water. It creates an air layer between the surface and the water that causes slip through two-phase flow. This allows the ship to slip past the water.

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Two potential reasons among others: the wind is not uniform, if it blows larger on one sector it will move the water surface stronger. Second, different smal surface waves that come from different directions can interfere either negatively or positively, depending on their relative phases, over some small region, which again wouls result in inhomoheneities ...

4

Here is a link to a study comparing heating water in a microwave to heating water in a conventional oven. Depending on the power of the microwave, the volume of the water, and time it's placed inside, the temperature will vary approximately linearly with time until either the system reaches equilibrium (for low power microwaves and large volumes of water) or ...

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I agree with Vladimir too. I tried both directions and both worked. I think that the shape of water basin may course. If it's true, there is a question. If water drain in different directions in Northern, Southern hemispheres which direction water drain in equator?

2

The coriolis acceleration is given by $a_c = -2 {\mathbf \omega} \times {\bf v}$, where $\omega$ is the angular velocity of the Earth and $v$ is the velocity of the water. The cross-product means that the largest this acceleration can be is $2\omega v$. If we assume the swirling water moves at maybe 0.1 m/s and $\omega = 2\pi/86400$ rad/s; then $a_c = 7 ... 0 I agree with Vladmimir, but want to add two more points 1) if you run water out and twist it one way with your hand it will run out that way, but then if you twist it the other way it flows out the other way - an experiment to try at home. 2) In the atmosphere the Coriolis effect does change the way air flows around a depression (region of low pressure) ... 1 It is not true. I tried both directions and both worked. It depends, therefore, on the initial conditions. 0 I don't believe that this would be necessary. Most pumps (not constant volume ones) have a relationship between flow rate and pressure jump (often called a pump curve). Since the entrance diameter of the pump doesn't change, you've got (basically) the same momentum in the pipe at a given flow rate regardless of how it gets that way. Another way of looking ... 1 Yes, the question is theoretical and so the response. Under enough pressure water will become a solid, regardless of temperature. That is, as far as it is still water. If pressure is high enough, the atoms will collapse and form neutron-degenerate matter (theorized to exist in the cores of neutron stars). I am not sure if there could be an intermediate mixed ... 1 In 1999, the president of the IEEE Power Engineering Society, Robert Dent, noted that: "The degree or intensity of the corona discharge and the resulting audible noise are affected by the condition of the air--that is, by humidity, air density, wind and water in the form of rain, drizzle and fog. Water increases the conductivity of the air and so ... 1 Shallow ponds will freeze all the way to the bottom (less than 5 feet), but deeper bodies of water will not. This is because the ice that forms on the surface insulates the water below. The temperature at the bottom of the lake is slightly above freezing. The ground is also just slightly above freezing. The water cannot be cooled down any lower since the ... 0 Because the surface of the ocean cools faster than the bottom, in addition the bottom has greater preassure so it freezes at a lower temperature, comething that doesnt happenin a glass of water where the preassure difference is minimal. Plus there are subsurface hot currents, so the two systems are not equivalent at all. 1 The thesis you refer to puts values of 0.02 S on the conductivity of freshwater and 4 S for seawater. I'm assuming that the S here stands for the SI unit of Siemens per metre, the value of$\sim 5$Siemens per metre is one I have used for seawater in the past. Submarines communicate with frequencies as low as 100 Hz.To test for a "good conductor" we compare ... 0 Pascal used a serynge that allowed leakage of fluid, to demonstrate that increasing pressure at one point would increase pressure at all points. Although water is leaking, as Babou said, we can still consider the fluid enclosed, where, instead of holes (that allow leakage) we could use sensors to mesure pressure. Watch a Wolfram demonstration of the ... 1 An electromagnetic wave consists of an electric and magnetic field that moves through space. If the space that the wave moves through is filled with electric charges, such as the ions in salt water, then the electric field will start to push these charges around. This pushing requires energy, and this energy is drained from the electric field. This is the ... 3 This effect is called Capillary Action. Yes we do in fact observe it in nature in a large scale: How do you think plants are able to "suck up"1 water through its roots and send it to the leaves? One of the major forces responsible for it is capillary action. Here, have a quote from the article mentioned above: Wicking is the absorption of a liquid by a ... 3 As is given in Jamie's answer I'll assume the surface is a revolution about$r=0\$, that the mean curvature is proportional to the pressure difference, and that the radius of the cup is much larger than the inverse of this mean curvature. In this case the mean curvature can be specified as $$K_m = \frac{r''}{2(1+r'^2)^{\frac32}}$$ As in Jamie's answer the ...

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