All high heels counter the natural functionality of the foot, which can create skeleton/muscular problems if they are worn excessively. Stiletto heels are no exception, but some people assume that because they are thinner they must be worse for you. In fact, they are safer to wear than the other extreme of high heel fashion, the platform shoe. Despite their impracticality, their popularity remains undiminished - as Terry DeHavilland (UK shoe designer) has said, "people say they're bad for the feet but they're good for the mind. What's more important?"

Stiletto heels undoubtedly concentrate a large amount of force into a small area. The great pressure transmitted through such a heel (allegedly greater than that exerted by an elephant standing on one foot) can cause damage to carpets and floors. The stiletto heel will also sink into soft ground, making it impractical for outdoor wear on grass.

-taken from wikipedia.org

Tides are caused by a gravitational tug-of-war between the sun, moon, and earth. All objects exert gravitational pull on each other. The closer they are, or the larger they are, the greater the pull. All of the planets exert some gravitational pull on the earth. However, the pull of the moon and sun are most noticeable because the moon is so close to us and the sun is so big. It takes the earth 365 days to revolve around the sun. As it revolves around the sun, it spins, or rotates on its axis once every 24 hours. At the same time, the moon revolves around the earth once every 29 days. The gravitational pull of the sun holds the earth in orbit, while the gravitational pull of the earth keeps the moon in orbit. As a result of this gravitational attraction between the earth and the moon, the side of the earth facing the moon is pulled towards it. Solid objects like the ground and buildings are not distorted as much as liquids like the ocean. A bulge of water occurs on the side of the earth facing the moon. As the earth rotates around the sun, centrifugal force causes an equal bulge of water on the opposite side of the earth. Water is pulled away from these two sides of the earth to form these bulges, or high tides. This leaves a depression, or low spot, in the oceans between. These are the areas of low tides. Most areas of the earth have two high tides and low tides every day. These high and low tides are slightly more than 6 hours apart. In some areas, the high and the low tides are the same. However, the earth is tilted on its axis, so the bulges are sometimes unequal. Because of this, in the Southern California region, one of the high tides each day is higher and one of the low tides each day is lower than the other. It depends on where you are located in the earth’s surface whether your high and low tides are semidiurnal (the same tide twice a day) or semi diurnal mixed (different tides twice a day).

Taken from: http://www.usc.edu/org/seagrant/Education/IELessons/Docs/MoonAndTides.pdf

Q: What is a heart rate?
A: The average number of heart beats per minute; a heart beat is when the heart contracts to pump blood thru your system.

Q: What is a resting heart rate?
A: Resting heart rate is the number of beats in one minute while you are at a complete rest state. Your resting heart rate indicates your basic overall heart health and fitness level. The more conditioned your body is, the less effort it needs to make to pump blood thru your body.

Q: What is a recovery heart rate?
A: This is the heart rate your body will drop to after two minutes, after stopping an exercise session. For instance you exercised for 30 minutes and your heart rate was at 155. Two minutes after you stopped exercising, your heart rate then decreased to 95. This recovery heart rate measure helps to evaluate your overall heart fitness level. Use this measurement to compare between exercise sessions

Q: What is a maximum heart rate?
A: A maximum heart rate (Max HR) is the highest number of beats your heart contracts during a one minute measurement. Max HR is a useful tool to measure training intensities and typically is used to measure or predict the level of exercise. It's always good to measure your Max HR while doing exercises to ensure you stay within a safe range or use it to measure if the exercise is actually working well enough to raise your heart rate to acceptable ranges and levels.

Q: How do I measure a Max HR?
A: The best method of determining your individual maximum heart rate is to be clinically tested and monitored on a treadmill. This is called a treadmill stress testing and is done by a cardiologist or certified physical therapist. Based on your age and physical condition, a formula is used to predict your Max HR. The other method is by using an age-predicted maximum heart rate formula:

WOMEN: 226 - your age = age-adjusted Max HR
MEN: 220 - your age = age-adjusted Max HR

Example: If you are a 30-year-old woman, your age-adjusted maximum heart rate is 226- 30 years = 196 bpm (beats per minute).

*note that this formula allows you to estimate your Max HR. Be sure to consult with your exercise trainer and doctors for the most effective rates that are customized to your health.

Heart Rate Charts:
Heart Rate Chart: Babies to Adults
AGE Beats Per Minute (BPM)
Babies to Age 1 100 - 160
Children ages 1-10 60 - 140
Children age 10+ and adults 60 - 100
Athletes: 40 - 60

Taken from: http://www.heart.com/heart-rate-chart.html

A sphere is a three-dimensional circle. Or you could say that a sphere is the set of all the points that are at the same distance from the center of the sphere. In nature, centrifugal force and gravity tend to make a lot of things into spheres: soap bubbles, for instance, atoms, and planets.

The radius of a sphere is the distance from its center to any point on its surface. The surface area of a sphere is the set of all the points on the outside of the sphere. To figure out what the surface area of a sphere is, you multiply the radius by itself and then multiply that by pi, so the formula is 4πr2. This is because the area is the length times the width (just like the area of a square). The width of a sphere is its diameter (twice the radius, or 2r). The length of a sphere is its circumference (2πr). So the width times the length, or the area, is 2r times 2πr, or 4πr2.

To figure out the volume of a sphere (how much air or water it would take to fill it up), you multiply the radius by itself and then by itself again, and then by pi, and then by 4, and divide the whole thing by 3. So the formula for the volume of a sphere is 4πr3/3.

Source: http://www.historyforkids.org/scienceforkids/math/geometry/sphere.htm

On August 12, 2000, the Russian Oscar II class submarine, Kursk sank in the Barents Sea. The generally accepted theory is that a leak of hydrogen peroxide in the forward torpedo room led to the detonation of a torpedo warhead, which in turn triggered the explosion of half a dozen other warheads about two minutes later. This second explosion was equivalent to about 3-7 tons of TNT and was large enough to register on seismographs across Northern Europe. Despite a rescue attempt by British and Norwegian teams, all 118 sailors and officers aboard Kursk were lost. A Dutch team later recovered the wreckage and all of the bodies, which were laid to rest in Russia.

More information on the explosion:
The tragedy began on the morning of August 12, 2000. As part of a naval exercise, Kursk was to fire two dummy torpedoes at a Kirov-class battlecruiser, Peter the Great, the flagship of the Northern Fleet. At 11:28 local time (07:28 UTC), high test peroxide (HTP), a form of highly concentrated hydrogen peroxide used as propellant for the torpedo, seeped through rust in the torpedo casing. The HTP reacted with copper and brass in the tube from which the torpedo was to be fired, causing a chain reaction leading to a chemical explosion. A similar incident was responsible for the loss of HMS Sidon in 1959. The watertight door separating the torpedo room from the rest of the submarine was left open prior to firing. This was apparently common practice, due to the amount of compressed air released into the torpedo room when a torpedo was launched. The open door allowed the blast to rip back through the first two of nine compartments on the huge submarine, probably killing the seven men in the first compartment, and at least injuring or disorienting the thirty-six men in the second compartment. After the first explosion, due to the fact the air conditioning duct was quite light, the blast wave traveled to more compartments, including the command post, filling them with smoke and flames. After the explosion, the captain was believed to be trying to order an 'emergency blow' which causes the sub to rapidly rise to the surface, but he was quickly overcome with smoke. An emergency buoy, designed to release from a submarine automatically when emergency conditions such as rapidly changing pressure or fire are detected and intended to help rescuers locate the stricken vessel, also failed to deploy. The previous summer, in a Mediterranean mission, fears of the buoy accidentally deploying, and thereby revealing the sub's position to the U.S. fleet, had led to the buoy being disabled. Two minutes and fifteen seconds after the initial eruption, a much larger explosion ripped through the submarine. Seismic data from stations across Northern Europe show that the explosion occurred at the same depth as the sea bed, suggesting that the submarine had collided with the sea floor which, combined with rising temperatures due to the initial explosion, had caused other torpedoes to explode. The second explosion was equivalent to 3–7 tons of TNT, or about a half-dozen torpedo warheads and measured 3.5 on the Richter scale. After the second explosion, the nuclear reactors were shut down to prevent a nuclear disaster, although the blast was almost enough to destroy the reactors. The second explosion ripped a two-metre-square hole in the hull of the craft, which was designed to withstand depths of 1000 meters. The explosion also ripped open the third and fourth compartments. Water poured into these compartments at 90,000 litres per second – killing all those in the compartments, including five officers from 7th SSGN Division Headquarters. The fifth compartment contained the ship's nuclear reactors, encased in a further five inches of steel. The bulkheads of the fifth compartment withstood the explosion, causing the nuclear control rods to stay in place and prevent nuclear disaster. Twenty-three men working in the sixth through to ninth compartments survived the two blasts. They gathered in the ninth compartment, which contained the secondary escape tunnel (the primary tunnel was in the destroyed second compartment). Captain-lieutenant Dmitri Kolesnikov (one of three officers of that rank surviving) appears to have taken charge, writing down the names of those who were in the ninth compartment. The air pressure in the compartment following the second explosion was still normal surface pressure. Thus it would be possible from a physiological point of view to use the escape hatch to leave the submarine one man at a time, swimming up through 100 metres of Arctic water in a survival suit, to await help floating at the surface. It is not known if the escape hatch was workable from the inside – opinions still differ about how badly the hatch was damaged. However it is likely that the men rejected using the perilous escape hatch even if it were operable. They may have preferred instead to take their chances waiting for a rescue vessel to clamp itself onto the escape hatch. It is not known with certainty how long the remaining men survived in the compartment. As the nuclear reactors had automatically shut down, emergency power soon ran out, plunging the crew into complete blackness and falling temperatures. Kolesnikov wrote two further messages, much less tidily than before. In the last, he wrote:

"It's dark here to write, but I'll try by feel. It seems like there are no chances, 10-20%. Let's hope that at least someone will read this. Here's the list of personnel from the other sections, who are now in the ninth and will attempt to get out. Regards to everybody, no need to be desperate. Kolesnikov."
There has been much debate over how long the sailors might have survived. Some, particularly on the Russian side, say that they would have died very quickly; water is known to leak into a stationary Oscar-II craft through the propeller shafts and at 100m depth it would have been impossible to plug these. Others point out that the many superoxide chemical cartridges, used to absorb carbon dioxide and chemically release oxygen to enable survival, were found used when the craft was recovered, suggesting that they had survived for several days. Ironically, the cartridges appear to have been the cause of death; a sailor appears to have accidentally brought a cartridge in contact with the sea water, causing a chemical reaction and a flash fire. The official investigation into the disaster showed that some men appeared to have survived the fire by plunging under the water (the fire marks on the walls indicate the water was at waist level in the lower area at this time). However the fire rapidly used up the remaining oxygen in the air, causing death by asphyxiation. According to Raising Kursk broadcast by the Science Channel: "In June of 2002, the Russian Navy recovered Kursk's bow section. Shortly afterwards, the Russian government investigation into the accident officially concluded that a faulty torpedo sank Kursk in the Summer of 2000."

1) attach weights to it (so it doesn't float)
2) place it in a volume of water
3) measure the change in height of the water level
4) take it all out
5) put just the weights in
6) measure the change in height of the water level
7) subtract 6) from 3)
8) convert height to volume by measuring the cross-sectional area of the container

Source:
http://answers.yahoo.com/question/index?qid=20081015183719AAMnQsp

­A submarine or a ship can float because the weight of water that it displaces is equal to the­ weight of the ship. This displacement of water creates an upward force called the buoyant force and acts opposite to gravity, which would pull the ship down. Unlike a ship, a submarine can control its buoyancy, thus allowing it to sink and surface at will.

To control its buoyancy, the submarine has ballast tanks and auxiliary, or trim tanks, that can be alternately filled with water or air (see animation below). When the submarine is on the surface, the ballast tanks are filled with air and the submarine's overall density is less than that of the surrounding water. As the submarine dives, the ballast tanks are flooded with water and the air in the ballast tanks is vented from the submarine until its overall density is greater than the surrounding water and the submarine begins to sink (negative buoyancy). A supply of compressed air is maintained aboard the submarine in air flasks for life support and for use with the ballast tanks. In addition, the submarine has movable sets of short "wings" called hydroplanes on the stern (back) that help to control the angle of the dive. The hydroplanes are angled so that water moves over the stern, which forces the stern upward; therefore, the submarine is angled downward.

To keep the submarine level at any set depth, the submarine maintains a balance of air and water in the trim tanks so that its overall density is equal to the surrounding water (neutral buoyancy). When the submarine reaches its cruising depth, the hydroplanes are leveled so that the submarine travels level through the water. Water is also forced between the bow and stern trim tanks to keep the sub level. The submarine can steer in the water by using the tail rudder to turn starboard (right) or port (left) and the hydroplanes to control the fore-aft angle of the submarine. In addition, some submarines are equipped with a retractable secondary propulsion motor that can swivel 360 degrees.

When the submarine surfaces, compressed air flows from the air flasks into the ballast tanks and the water is forced out of the submarine until its overall density is less than the surrounding water (positive buoyancy) and the submarine rises. The hydroplanes are angled so that water moves up over the stern, which forces the stern downward; therefore, the submarine is angled upward. In an emergency, the ballast tanks can be filled quickly with high-pressure air to take the submarine to the surface very rapidly.

Taken From: http://science.howstuffworks.com/submarine1.htm

Absolute zero is the point where no more heat can be removed from a system, according to the absolute or thermodynamic temperature scale. This corresponds to 0 K or -273.15°C. In classical kinetic theory, there should be no movement of individual molecules at absolute zero, but experimental evidences shows this isn't the case.
Temperature is used to describe how hot or cold an object it. The temperature of an object depends on how fast its atoms and molecules oscillate. At absolute zero, these oscillations are the slowest they can possibly be. Even at absolute zero, the motion doesn't completely stop.

It's not possible to reach absolute zero, though scientists have approached it. The NIST achieved a record cold temperature of 700 nK (billionths of a Kelvin) in 1994. MIT researchers set a new record of 0.45 nK in 2003.

Sources:
http://chemistry.about.com/od/chemistryfaqs/f/absolutezero.htm
http://www.cartage.org.lb/en/themes/Sciences/Physics/Cryogenics/AbsoluteZero/absolutezero/AbsoluteZero.jpg

Although a ship is made up of metal and metal is more dense than water, its hull is filled with air which is so much more less dense than water that it makes up for the density of the metal and ends up being less dense than water.

Foundation of a Meniscus:


When liquid water is confined in a tube, its surface (meniscus) has a concave shape because water wets the surface and creeps up the side.

However...for another example:


Mercury does not wet glass - the cohesive forces within the drops are stronger than the adhesive forces between the drops and glass. When liquid mercury is confined in a tube, its surface (meniscus) has a convex shape because the cohesive forces in liquid mercury tend to draw it into a drop.

To read more about meniscus and surface tension...:
http://www.chem.purdue.edu/gchelp/liquids/tension.html
http://en.wikipedia.org/wiki/Surface_tension
http://www.tutorvista.com/ks/meniscus-surface-tension

As we all know...
Anything with a higher density than water will sink in water.

The human body is, by weight, approximately two-thirds of water. That means our density is similar to that of water.

So why do we tend to float when we hold our breath, and sink when we breathe? For example when we go underwater while holding our breath, we try to touch the bottom, but it is very hard to do so because naturally, we'll float back up. However when we breathe out we tend to sink.

Well, oxygen is less dense than water. So, of course, the more oxygen you have in your body, the more buoyant you'll be. Hence, when you take a deep breath and hold it, there's more oxygen in your body and so you'll float since oxygen is less dense than water.

The dead sea is also called the Salt Sea, because it is one of the world's saltiest bodies of water, with 33.7% salinity. Because of this, animals are unable to live in the dead sea, hence its name.

So why do you float on the dead sea?
Well, since there is so much salt in the dead sea, the water there is very dense compared to fresh water or ordinary seawater. Also, less objects or surface floats in the water. That means that we're less dense, so we can float on the dead sea.

Sources:
http://en.wikipedia.org/wiki/Dead_Sea
http://wiki.answers.com/Q/Why_do_you_float_on_the_Dead_Sea
http://en.wikipedia.org/wiki/File:Dead_sea_newspaper.jpg

Why does the orange float, but when the peel is removed, sinks?

Because the inside of the orange is denser than water! A good example is like a rock wrapped in a life preserver. Take away the life preserver and the rock sinks. It's just like the orange. Take away the peel and the orange sinks.

The inside of the orange is denser than water as although it is mostly made up of water (the tasty juice =D) but there's dissolved sugar and other flavourful compounds which are heavier than water molecules that they displace. The result is the orange juice weighs more than the same volume of water.

An experiment to try:
Try floating diet soda and soda containing sugar in a bowl of water! Only one of them will float. :)

All high heels counter the natural functionality of the foot, which can create skeleton/muscular problems if they are worn excessively. Stiletto heels are no exception, but some people assume that because they are thinner they must be worse for you. In fact, they are safer to wear than the other extreme of high heel fashion, the platform shoe. Despite their impracticality, their popularity remains undiminished - as Terry DeHavilland (UK shoe designer) has said, "people say they're bad for the feet but they're good for the mind. What's more important?"

Stiletto heels undoubtedly concentrate a large amount of force into a small area. The great pressure transmitted through such a heel (allegedly greater than that exerted by an elephant standing on one foot) can cause damage to carpets and floors. The stiletto heel will also sink into soft ground, making it impractical for outdoor wear on grass.

-taken from wikipedia.org

Tides are caused by a gravitational tug-of-war between the sun, moon, and earth. All objects exert gravitational pull on each other. The closer they are, or the larger they are, the greater the pull. All of the planets exert some gravitational pull on the earth. However, the pull of the moon and sun are most noticeable because the moon is so close to us and the sun is so big. It takes the earth 365 days to revolve around the sun. As it revolves around the sun, it spins, or rotates on its axis once every 24 hours. At the same time, the moon revolves around the earth once every 29 days. The gravitational pull of the sun holds the earth in orbit, while the gravitational pull of the earth keeps the moon in orbit. As a result of this gravitational attraction between the earth and the moon, the side of the earth facing the moon is pulled towards it. Solid objects like the ground and buildings are not distorted as much as liquids like the ocean. A bulge of water occurs on the side of the earth facing the moon. As the earth rotates around the sun, centrifugal force causes an equal bulge of water on the opposite side of the earth. Water is pulled away from these two sides of the earth to form these bulges, or high tides. This leaves a depression, or low spot, in the oceans between. These are the areas of low tides. Most areas of the earth have two high tides and low tides every day. These high and low tides are slightly more than 6 hours apart. In some areas, the high and the low tides are the same. However, the earth is tilted on its axis, so the bulges are sometimes unequal. Because of this, in the Southern California region, one of the high tides each day is higher and one of the low tides each day is lower than the other. It depends on where you are located in the earth’s surface whether your high and low tides are semidiurnal (the same tide twice a day) or semi diurnal mixed (different tides twice a day).

Taken from: http://www.usc.edu/org/seagrant/Education/IELessons/Docs/MoonAndTides.pdf

Q: What is a heart rate?
A: The average number of heart beats per minute; a heart beat is when the heart contracts to pump blood thru your system.

Q: What is a resting heart rate?
A: Resting heart rate is the number of beats in one minute while you are at a complete rest state. Your resting heart rate indicates your basic overall heart health and fitness level. The more conditioned your body is, the less effort it needs to make to pump blood thru your body.

Q: What is a recovery heart rate?
A: This is the heart rate your body will drop to after two minutes, after stopping an exercise session. For instance you exercised for 30 minutes and your heart rate was at 155. Two minutes after you stopped exercising, your heart rate then decreased to 95. This recovery heart rate measure helps to evaluate your overall heart fitness level. Use this measurement to compare between exercise sessions

Q: What is a maximum heart rate?
A: A maximum heart rate (Max HR) is the highest number of beats your heart contracts during a one minute measurement. Max HR is a useful tool to measure training intensities and typically is used to measure or predict the level of exercise. It's always good to measure your Max HR while doing exercises to ensure you stay within a safe range or use it to measure if the exercise is actually working well enough to raise your heart rate to acceptable ranges and levels.

Q: How do I measure a Max HR?
A: The best method of determining your individual maximum heart rate is to be clinically tested and monitored on a treadmill. This is called a treadmill stress testing and is done by a cardiologist or certified physical therapist. Based on your age and physical condition, a formula is used to predict your Max HR. The other method is by using an age-predicted maximum heart rate formula:

WOMEN: 226 - your age = age-adjusted Max HR
MEN: 220 - your age = age-adjusted Max HR

Example: If you are a 30-year-old woman, your age-adjusted maximum heart rate is 226- 30 years = 196 bpm (beats per minute).

*note that this formula allows you to estimate your Max HR. Be sure to consult with your exercise trainer and doctors for the most effective rates that are customized to your health.

Heart Rate Charts:
Heart Rate Chart: Babies to Adults
AGE Beats Per Minute (BPM)
Babies to Age 1 100 - 160
Children ages 1-10 60 - 140
Children age 10+ and adults 60 - 100
Athletes: 40 - 60

Taken from: http://www.heart.com/heart-rate-chart.html

A sphere is a three-dimensional circle. Or you could say that a sphere is the set of all the points that are at the same distance from the center of the sphere. In nature, centrifugal force and gravity tend to make a lot of things into spheres: soap bubbles, for instance, atoms, and planets.

The radius of a sphere is the distance from its center to any point on its surface. The surface area of a sphere is the set of all the points on the outside of the sphere. To figure out what the surface area of a sphere is, you multiply the radius by itself and then multiply that by pi, so the formula is 4πr2. This is because the area is the length times the width (just like the area of a square). The width of a sphere is its diameter (twice the radius, or 2r). The length of a sphere is its circumference (2πr). So the width times the length, or the area, is 2r times 2πr, or 4πr2.

To figure out the volume of a sphere (how much air or water it would take to fill it up), you multiply the radius by itself and then by itself again, and then by pi, and then by 4, and divide the whole thing by 3. So the formula for the volume of a sphere is 4πr3/3.

Source: http://www.historyforkids.org/scienceforkids/math/geometry/sphere.htm

On August 12, 2000, the Russian Oscar II class submarine, Kursk sank in the Barents Sea. The generally accepted theory is that a leak of hydrogen peroxide in the forward torpedo room led to the detonation of a torpedo warhead, which in turn triggered the explosion of half a dozen other warheads about two minutes later. This second explosion was equivalent to about 3-7 tons of TNT and was large enough to register on seismographs across Northern Europe. Despite a rescue attempt by British and Norwegian teams, all 118 sailors and officers aboard Kursk were lost. A Dutch team later recovered the wreckage and all of the bodies, which were laid to rest in Russia.

More information on the explosion:
The tragedy began on the morning of August 12, 2000. As part of a naval exercise, Kursk was to fire two dummy torpedoes at a Kirov-class battlecruiser, Peter the Great, the flagship of the Northern Fleet. At 11:28 local time (07:28 UTC), high test peroxide (HTP), a form of highly concentrated hydrogen peroxide used as propellant for the torpedo, seeped through rust in the torpedo casing. The HTP reacted with copper and brass in the tube from which the torpedo was to be fired, causing a chain reaction leading to a chemical explosion. A similar incident was responsible for the loss of HMS Sidon in 1959. The watertight door separating the torpedo room from the rest of the submarine was left open prior to firing. This was apparently common practice, due to the amount of compressed air released into the torpedo room when a torpedo was launched. The open door allowed the blast to rip back through the first two of nine compartments on the huge submarine, probably killing the seven men in the first compartment, and at least injuring or disorienting the thirty-six men in the second compartment. After the first explosion, due to the fact the air conditioning duct was quite light, the blast wave traveled to more compartments, including the command post, filling them with smoke and flames. After the explosion, the captain was believed to be trying to order an 'emergency blow' which causes the sub to rapidly rise to the surface, but he was quickly overcome with smoke. An emergency buoy, designed to release from a submarine automatically when emergency conditions such as rapidly changing pressure or fire are detected and intended to help rescuers locate the stricken vessel, also failed to deploy. The previous summer, in a Mediterranean mission, fears of the buoy accidentally deploying, and thereby revealing the sub's position to the U.S. fleet, had led to the buoy being disabled. Two minutes and fifteen seconds after the initial eruption, a much larger explosion ripped through the submarine. Seismic data from stations across Northern Europe show that the explosion occurred at the same depth as the sea bed, suggesting that the submarine had collided with the sea floor which, combined with rising temperatures due to the initial explosion, had caused other torpedoes to explode. The second explosion was equivalent to 3–7 tons of TNT, or about a half-dozen torpedo warheads and measured 3.5 on the Richter scale. After the second explosion, the nuclear reactors were shut down to prevent a nuclear disaster, although the blast was almost enough to destroy the reactors. The second explosion ripped a two-metre-square hole in the hull of the craft, which was designed to withstand depths of 1000 meters. The explosion also ripped open the third and fourth compartments. Water poured into these compartments at 90,000 litres per second – killing all those in the compartments, including five officers from 7th SSGN Division Headquarters. The fifth compartment contained the ship's nuclear reactors, encased in a further five inches of steel. The bulkheads of the fifth compartment withstood the explosion, causing the nuclear control rods to stay in place and prevent nuclear disaster. Twenty-three men working in the sixth through to ninth compartments survived the two blasts. They gathered in the ninth compartment, which contained the secondary escape tunnel (the primary tunnel was in the destroyed second compartment). Captain-lieutenant Dmitri Kolesnikov (one of three officers of that rank surviving) appears to have taken charge, writing down the names of those who were in the ninth compartment. The air pressure in the compartment following the second explosion was still normal surface pressure. Thus it would be possible from a physiological point of view to use the escape hatch to leave the submarine one man at a time, swimming up through 100 metres of Arctic water in a survival suit, to await help floating at the surface. It is not known if the escape hatch was workable from the inside – opinions still differ about how badly the hatch was damaged. However it is likely that the men rejected using the perilous escape hatch even if it were operable. They may have preferred instead to take their chances waiting for a rescue vessel to clamp itself onto the escape hatch. It is not known with certainty how long the remaining men survived in the compartment. As the nuclear reactors had automatically shut down, emergency power soon ran out, plunging the crew into complete blackness and falling temperatures. Kolesnikov wrote two further messages, much less tidily than before. In the last, he wrote:

"It's dark here to write, but I'll try by feel. It seems like there are no chances, 10-20%. Let's hope that at least someone will read this. Here's the list of personnel from the other sections, who are now in the ninth and will attempt to get out. Regards to everybody, no need to be desperate. Kolesnikov."
There has been much debate over how long the sailors might have survived. Some, particularly on the Russian side, say that they would have died very quickly; water is known to leak into a stationary Oscar-II craft through the propeller shafts and at 100m depth it would have been impossible to plug these. Others point out that the many superoxide chemical cartridges, used to absorb carbon dioxide and chemically release oxygen to enable survival, were found used when the craft was recovered, suggesting that they had survived for several days. Ironically, the cartridges appear to have been the cause of death; a sailor appears to have accidentally brought a cartridge in contact with the sea water, causing a chemical reaction and a flash fire. The official investigation into the disaster showed that some men appeared to have survived the fire by plunging under the water (the fire marks on the walls indicate the water was at waist level in the lower area at this time). However the fire rapidly used up the remaining oxygen in the air, causing death by asphyxiation. According to Raising Kursk broadcast by the Science Channel: "In June of 2002, the Russian Navy recovered Kursk's bow section. Shortly afterwards, the Russian government investigation into the accident officially concluded that a faulty torpedo sank Kursk in the Summer of 2000."

1) attach weights to it (so it doesn't float)
2) place it in a volume of water
3) measure the change in height of the water level
4) take it all out
5) put just the weights in
6) measure the change in height of the water level
7) subtract 6) from 3)
8) convert height to volume by measuring the cross-sectional area of the container

Source:
http://answers.yahoo.com/question/index?qid=20081015183719AAMnQsp

­A submarine or a ship can float because the weight of water that it displaces is equal to the­ weight of the ship. This displacement of water creates an upward force called the buoyant force and acts opposite to gravity, which would pull the ship down. Unlike a ship, a submarine can control its buoyancy, thus allowing it to sink and surface at will.

To control its buoyancy, the submarine has ballast tanks and auxiliary, or trim tanks, that can be alternately filled with water or air (see animation below). When the submarine is on the surface, the ballast tanks are filled with air and the submarine's overall density is less than that of the surrounding water. As the submarine dives, the ballast tanks are flooded with water and the air in the ballast tanks is vented from the submarine until its overall density is greater than the surrounding water and the submarine begins to sink (negative buoyancy). A supply of compressed air is maintained aboard the submarine in air flasks for life support and for use with the ballast tanks. In addition, the submarine has movable sets of short "wings" called hydroplanes on the stern (back) that help to control the angle of the dive. The hydroplanes are angled so that water moves over the stern, which forces the stern upward; therefore, the submarine is angled downward.

To keep the submarine level at any set depth, the submarine maintains a balance of air and water in the trim tanks so that its overall density is equal to the surrounding water (neutral buoyancy). When the submarine reaches its cruising depth, the hydroplanes are leveled so that the submarine travels level through the water. Water is also forced between the bow and stern trim tanks to keep the sub level. The submarine can steer in the water by using the tail rudder to turn starboard (right) or port (left) and the hydroplanes to control the fore-aft angle of the submarine. In addition, some submarines are equipped with a retractable secondary propulsion motor that can swivel 360 degrees.

When the submarine surfaces, compressed air flows from the air flasks into the ballast tanks and the water is forced out of the submarine until its overall density is less than the surrounding water (positive buoyancy) and the submarine rises. The hydroplanes are angled so that water moves up over the stern, which forces the stern downward; therefore, the submarine is angled upward. In an emergency, the ballast tanks can be filled quickly with high-pressure air to take the submarine to the surface very rapidly.

Taken From: http://science.howstuffworks.com/submarine1.htm

Absolute zero is the point where no more heat can be removed from a system, according to the absolute or thermodynamic temperature scale. This corresponds to 0 K or -273.15°C. In classical kinetic theory, there should be no movement of individual molecules at absolute zero, but experimental evidences shows this isn't the case.
Temperature is used to describe how hot or cold an object it. The temperature of an object depends on how fast its atoms and molecules oscillate. At absolute zero, these oscillations are the slowest they can possibly be. Even at absolute zero, the motion doesn't completely stop.

It's not possible to reach absolute zero, though scientists have approached it. The NIST achieved a record cold temperature of 700 nK (billionths of a Kelvin) in 1994. MIT researchers set a new record of 0.45 nK in 2003.

Sources:
http://chemistry.about.com/od/chemistryfaqs/f/absolutezero.htm
http://www.cartage.org.lb/en/themes/Sciences/Physics/Cryogenics/AbsoluteZero/absolutezero/AbsoluteZero.jpg

Although a ship is made up of metal and metal is more dense than water, its hull is filled with air which is so much more less dense than water that it makes up for the density of the metal and ends up being less dense than water.

Foundation of a Meniscus:


When liquid water is confined in a tube, its surface (meniscus) has a concave shape because water wets the surface and creeps up the side.

However...for another example:


Mercury does not wet glass - the cohesive forces within the drops are stronger than the adhesive forces between the drops and glass. When liquid mercury is confined in a tube, its surface (meniscus) has a convex shape because the cohesive forces in liquid mercury tend to draw it into a drop.

To read more about meniscus and surface tension...:
http://www.chem.purdue.edu/gchelp/liquids/tension.html
http://en.wikipedia.org/wiki/Surface_tension
http://www.tutorvista.com/ks/meniscus-surface-tension

As we all know...
Anything with a higher density than water will sink in water.

The human body is, by weight, approximately two-thirds of water. That means our density is similar to that of water.

So why do we tend to float when we hold our breath, and sink when we breathe? For example when we go underwater while holding our breath, we try to touch the bottom, but it is very hard to do so because naturally, we'll float back up. However when we breathe out we tend to sink.

Well, oxygen is less dense than water. So, of course, the more oxygen you have in your body, the more buoyant you'll be. Hence, when you take a deep breath and hold it, there's more oxygen in your body and so you'll float since oxygen is less dense than water.

The dead sea is also called the Salt Sea, because it is one of the world's saltiest bodies of water, with 33.7% salinity. Because of this, animals are unable to live in the dead sea, hence its name.

So why do you float on the dead sea?
Well, since there is so much salt in the dead sea, the water there is very dense compared to fresh water or ordinary seawater. Also, less objects or surface floats in the water. That means that we're less dense, so we can float on the dead sea.

Sources:
http://en.wikipedia.org/wiki/Dead_Sea
http://wiki.answers.com/Q/Why_do_you_float_on_the_Dead_Sea
http://en.wikipedia.org/wiki/File:Dead_sea_newspaper.jpg

Why does the orange float, but when the peel is removed, sinks?

Because the inside of the orange is denser than water! A good example is like a rock wrapped in a life preserver. Take away the life preserver and the rock sinks. It's just like the orange. Take away the peel and the orange sinks.

The inside of the orange is denser than water as although it is mostly made up of water (the tasty juice =D) but there's dissolved sugar and other flavourful compounds which are heavier than water molecules that they displace. The result is the orange juice weighs more than the same volume of water.

An experiment to try:
Try floating diet soda and soda containing sugar in a bowl of water! Only one of them will float. :)