What is the principle involved in level control? i am required to do a experiment to control the water level.?
825040
a simple system would be a float connected to the valve like in the back tank of a residential flush toilet.  This does not maintain precise level- the tank goes nearly empty and then spends some time refilling.\n\nprecise level control like in an chemical process situation would have a level sensor with a 4-20 milliamp output.  as the level changes, the output signal gets stronger and stronger.  The contorller opens the valve a little on a weak signal and the valves opesn more fully as the signal gets stronger.  This of course was based on a control valve to fill the tank.\n\nyou could do a similar methodolgy on a tank draining valve- as the tank fills from some other source the valve opens and lets liquid out to maintain the level.
89807
1. you need firstly to have a total density equivalent to that of fresh or salt water(for whatever purposed required)\nthen bouyancy will be stable/maintained \nthis will make a suitable start\n2. forge a shape suitable to make the sub hydrodynamic, this will enable the prototype to glige through the water \n3. have fun!
511310
How do we measure sea level?  \nThe first way to measure sea level is with a water level meter found in a water level station on the coast. \na) An old style water level station: this meter consists of a simple, large ruler. An observer can read the water level in feet on the ruler and record the measurement. \n\nb) Newer water level stations: contains a new electronic water level sensor. \n- Operates by transmitting a series of ultrasonic sound waves in a cone shaped pattern. \n- Sound waves reflect from the target (such as water level) back to the sensor, which measures the time interval between transmitting and receiving the sound wave. \n- Calculated by the speed of sound, the time interval is converted to a distance measurement. \n- This device then transmits the measurement data by satellite to NOAA, where it is displayed on their website. \n\nThe second way to measure sea level is with a satellite:\nThe spacecraft's radar altimeters measure the precise distance between the satellite and sea surface by measuring the round-trip travel time of microwave pulses bounced from the spacecraft to the sea surface and back to the spacecraft. The altitude of the satellite is determined by a sophisticated estimation procedure based on an orbit determination measurement system both onboard the satellite and on the ground all over the world. The details of the shape of the returned radar pulses give information on wind speed and the wave height. \nOur home, the Earth, experiences some of the most varied and interesting weather in the Solar System. This is because the Earth is actually a water-world, with some 70% of its surface covered by a vast, deep ocean. The world-ocean is a huge sink for solar energy. Through currents the ocean transports this energy as heat, and releases it back into the atmosphere as water vapor, which is then returned back to the oceans and land as rain or snow. This completes the hydrologic cycle. \n How can we measure and track changes in the oceanic heat-budget? We need to know both ocean currents and heat storage of the ocean. Like winds blow around the highs and lows of atmospheric pressure, ocean currents flow around highs and lows of oceanic pressure that can be determined from the height of sea surface, called ocean surface topography. Ocean current velocity can thus be computed from the slope of the ocean surface. Furthermore, as water heats up, it expands, and as it cools, it contracts, affecting the height of sea surface as well. Measuring the ocean surface topography thus gives the required information for studying global ocean circulation and the oceans heat budget. Regular scanning of the ocean surface to maintain a database of ocean surface topography can help predict short-term changes in weather and longer-term patterns of climate.
431380
If the pressure is 0.76m of Hg, it is equivalent to 10.3 m of water. There is a vacuum in the tube above this water height.\n\nHowever, by “vacuum” we mean inside this space, the pressure is low. There will be vapour of water which will have some pressure.\n\nEven in mercury barometer, there will be mercury vapour inside the “Torricelli’s vacuum”.  \n\nThis is the reason that ordinary pump which sucks water from a well or sump is not able to lift water to a height more than 10m from the surface of the water.
993273
Process Electrolysis\n\nYou will need two ordinary glasses, A pan , a DC electrical source and some supports to support the glasses in the pan with the rim below the water level.\n\nYou can find a simple experiment  and details here : http://en.wikipedia.org/wiki/Electrolysis
905607
make a little "boat" that you can add weights to and float it in the different liquids.  Gradually add weight to the boat in each liquid to see how much it can hold before it sinks.  The more weight the boat can hold, the greater the density of the liquid!\n\nThis is basically a poor-man's hydrometer.
561534
Your question is a bit ambiguous, but let's see if we can answer and clarify:\n\n(1) There is a lake with a certain amount of water, thus establishing a water level with respect to the ground.\n(2) There is a boat with a coin inside it on the lake. The boat sinks into the lake to a level that you can mark on the side of the boat.\n(3) The coin is tossed into the lake, thus reducing the total weight of the boat and this will cause the "water level" wrt to the boat to change, i.e. the "water level" will decrease a bit since the boat will have risen a bit higher from the water surface.\n(4) When the boat with the coin inside it is floating on the lake, the lake's water level wrt to the ground will rise a bit, because the boat has displaced the lake's water.\n(5) When the coin is tossed into the lake, the water level wrt to the ground does change, but we do not know how because now the lake's water is being displaced by the coin's physical volume, not by its weight, as it was the case when it was inside the boat.
621304
If you are dealing with a reaction involving ammonium carbonate in solution, and are then measuring the temperature rise, you need the heat capacity of water, not ammonium carbonate!\n\nPlease post the whole problem if that is not enough to get you started.
663003
You want to capture the gravitational potential energy of the water and make it do mechanical work, which is converted to electricity.\n\nIn principle this does not require a dam - any natural flow of water can be turned into motion (as with a millwheel, for example).  A dam does this in a more efficient way.\n\n  First the dam raises the water level, increasing the energy available at that site.  Then the water is channelled to a device to turn its motion into spin (often the channels to the turbines are not in the dam itself but in the bedrock surounding the dam) - usually a bank of turbines, which extact the maximum energy from a stream of fluid by having each turbine take a little bit.  The spin drives a generator.
60733
simply use a hydrometer.
867250
Water level in order to Prevent floods, because you can change the flood prevention methods e.g put in higher banks, change flood gage. If the water is going over the normal flood level frequently. They have been around for years
641728
see how much weight each surface can hold up. I know u can keep a needle afloat in a cup of water. Although the experiment would depend on what kind of paper and how damp it was.
947952
Highlight the data and put your cursor at the bottom right of the lowset box, the cursor should turn into a small +. hold the cursor down and drag your mouse doun a few rows.  Once you let up on your mouse you should see the info you want.\n\nYes, if you increase pressure you can increase the temperature of the water, but it needs to be in a closed system, it's called super heating.
758989
An example: Boyle's law: pV = constant\nYou choose the volume V (the independent variable)\nWhen you change the volume, the pressure p changes by it: the dependent variable.\npV = constant is only true for constant T, so now the temperature must be the controlled variable; it must be constant.\n\nTh
731168
just measure how much water they lose to the atmosophere some how and keep track of the amount of water you have added over a period of time. \nThis should be an interseting experiment.
487009
Imagine a column of water.  The pressure is higher at the bottom of the column because of all the water above it pushing down.  Now, a closed water system can be treated as a column for determining the water pressure.  You measure from the highest point that water is in the system down to the height of the place where you taking the measurement.  \n\nIf the water tower is 200 feet tall and the building is 90 feet tall, the people on the top of the building will have 110 foot column forming their water pressure.  People in the bottom of the building will have the full 200 foot tall column of water forming their water pressure.  \n\nBecause we are dealing with a fluid, the water can exert its force around corners and the column doesn't have to really be straight up and down.  It can even have u-turns and loops.  All that really matters is the height of the faucet relative to the water level in the reservoir.
530819
Com'on people, you should know this.\n\nPut in the ice cube slowly, some water spills out, most of the ice is under water (about 92% due to lower density).  Ice melts in time and the water level drops very slightly due to: 1) water temperature drops a bit (higher density, lower volume), 2)evaporation.