Sunday, July 27, 2014
Thursday, July 24, 2014
Fluid pressure from gravity or acceleration
The weight of a fluid can exert a pressure on anything underneath it. Also, the relative movement of a liquid or gas can apply a pressure.
Pressure
Pressure is defined as force divided by the area on which the force is pushing. (See the lesson on Pressurefor details.) You can write this as an equation, if you wanted to make some calculations:
P = F/A
where
- P = pressure
- F = force
- A = area
- F/A = F divided by A
Pressure due to gravity
Since the weight of an object or material is equal to the force it excerts due to gravity,
An object can exert downward pressure due to its weight and the force of gravity. The pressure you exert on the floor is your weight divided by the area of the soles of your shoes. If the force is due to the weight (W) of the object, the equation is then: P = W / A
Water pressure
The water pressure at the bottom of a lake is equal to the weight of the column of water above divided by the area of that column.
Pressure at depth is Weight / Area
Column on top of head
If you were standing on the bottom of a swimming pool (assuming you would not start floating), there would be a column of water the diameter of your head all the way up to the water surface, pushing down on you. If you took that column of water and weighed it, and then divided that weight by the area of the top of your head, you would get the value for the water pressure on your head.
The reason it does not affect you is that your internal body pressure increases to neutralize most of the water pressure. But at greater depths, the water pressure can become so great that it can harm the diver.
Demonstration with can
A demonstration of how water pressure increases with the depth of the water can be done with a large tin can. Punch nail holes in a vertical line up the side of the can every inch or several centimeters. Then fill the can with water. The water may just dribble out the top holes, but the increased pressure with depth causes the water to squirt out with more pressure at the bottom holes.
Air pressure
Likewise, the air pressure on the top of your head is the weight of the column of air (which is several miles high) divided by the area of the top of your head. The average air pressure on your head is 16 pounds per square inch! That is a lot of weight you are holding up.
Air pressure in weather
When weather report indicates high pressure, that means the column of air reaches up higher than it does for a low pressure reader. A barometer measures the air pressure or the weight of the column of air.
Air pressure is due to the weight of all the air going several miles up above you. It is approximately 16 pounds per square inch in all directions on your body. Fortunately, our bodies have internal pressure that equalizes the air pressure.
Balloons
The air pressure inside a balloon pushes outward in all directions. When the pressure increases, the size of the balloon increases, until it finally bursts. The internal air pressure is much greater than the external air pressure.
Different altitudes
The normal air pressure in Denver, Colorado is less than in This is because the higher altitude of Denver means its column of air is not as high as in Milwaukee.
Since many snacks are sealed in pressurized bags, a bag sealed in Milwaukee requires higher internal pressure than one made in Denver. Thus a Milwaukee bag of snacks will expand when brought to the lower air pressure of Denver and could even explode.
Direction of fluid pressure
Now, what is different about pressure caused by a liquid, or gas is that not only is there pressure pushing down at a given point, but there is also the same pressure pushing up and to the sides.
All directions
The pressure is the same in all directions in a fluid at a given point. This is true because of the characteristic of liquids and gases to take the shape of their container.
Water pressure is the same in all directions
What this also means that any hollow container submersed in a liquid has pressure on every square inch of its surface, top and bottom.
Swimming under water
When you swim under water, the pressure of the water gets greater on your body, the deeper you get. Now, the question is: "Why aren't you crushed by all this weight?"
The reason is that your body compensates by creating an internal pressure that is equal to the air or water pressure. You are somewhat like a balloon filled with fluids under pressure. Now, when you go very deep under water, the water pressure may get greater than your body can compensate for, and you get uncomfortable.
Other pressure effects
Other effects of fluid pressure are motion, heating and chemical effects, as well as applications in the field of hydraulics and in aircraft.
(See Applications of Fluid Principles for details.)
Wind and current
The movement of a fluid, such as with wind or the current of a river can apply a pressure to an object in its way proportional to the surface area perpendicular to the direction of motion.
Streamlining the object reduces this pressure.
Heating and chemical effects
When you heat a fluid, it usually expands. If you heat a fluid that is in an enclosed container, the expansion will result in greater internal pressure. For example, heating a balloon will cause it to expand.
Likewise, chemical reactions that give off gases will increase the pressure inside the container. For example, shaking a carbonated drink bottle releases more gas and will result in greater internal pressure. This can be experienced when you open the bottle and the drink squirts all over.
Hydraulics
When a fluid—especially a liquid—is in a partially closed container, a force applied in one area can result in a greater force in another area. This effect is used in hydraulics to create a mechanical advantage by having the force applied to a small piston resulting in a greater force applied to large piston.
Aircraft
The scientist Bernoulli discovered that the air pressure in a tube goes down when the velocity of the air in the tube increases. This discovery became known as Bernoulli's Principle.
The greatest application of this principle is used in airplanes. The wing of an airplane is usually curved on top and flat on the bottom. When the air moves over the curved top portion of the wing, it speeds up because of the shape. This lowers the pressure with respect to the bottom part of the wing. Lower pressure on the top results in the lift required to keep the airplane aloft.
Summary
Fluid pressure from gravity is the weight of the fluid above divided by the area it is pushing on. Fluid pressure applies in all directions. Internal pressure of an object equals the external fluid pressure, otherwise the object could be crushed. Wind and heating can also create pressure.
Fluid pressure from gravity or acceleration
The weight of a fluid can exert a pressure on anything underneath it. Also, the relative movement of a liquid or gas can apply a pressure.
Pressure
Pressure is defined as force divided by the area on which the force is pushing. (See the lesson on Pressurefor details.) You can write this as an equation, if you wanted to make some calculations:
P = F/A
where
- P = pressure
- F = force
- A = area
- F/A = F divided by A
Pressure due to gravity
Since the weight of an object or material is equal to the force it excerts due to gravity,
An object can exert downward pressure due to its weight and the force of gravity. The pressure you exert on the floor is your weight divided by the area of the soles of your shoes. If the force is due to the weight (W) of the object, the equation is then: P = W / A
Water pressure
The water pressure at the bottom of a lake is equal to the weight of the column of water above divided by the area of that column.
Pressure at depth is Weight / Area
Column on top of head
If you were standing on the bottom of a swimming pool (assuming you would not start floating), there would be a column of water the diameter of your head all the way up to the water surface, pushing down on you. If you took that column of water and weighed it, and then divided that weight by the area of the top of your head, you would get the value for the water pressure on your head.
The reason it does not affect you is that your internal body pressure increases to neutralize most of the water pressure. But at greater depths, the water pressure can become so great that it can harm the diver.
Demonstration with can
A demonstration of how water pressure increases with the depth of the water can be done with a large tin can. Punch nail holes in a vertical line up the side of the can every inch or several centimeters. Then fill the can with water. The water may just dribble out the top holes, but the increased pressure with depth causes the water to squirt out with more pressure at the bottom holes.
Air pressure
Likewise, the air pressure on the top of your head is the weight of the column of air (which is several miles high) divided by the area of the top of your head. The average air pressure on your head is 16 pounds per square inch! That is a lot of weight you are holding up.
Air pressure in weather
When weather report indicates high pressure, that means the column of air reaches up higher than it does for a low pressure reader. A barometer measures the air pressure or the weight of the column of air.
Air pressure is due to the weight of all the air going several miles up above you. It is approximately 16 pounds per square inch in all directions on your body. Fortunately, our bodies have internal pressure that equalizes the air pressure.
Balloons
The air pressure inside a balloon pushes outward in all directions. When the pressure increases, the size of the balloon increases, until it finally bursts. The internal air pressure is much greater than the external air pressure.
Different altitudes
The normal air pressure in Denver, Colorado is less than in This is because the higher altitude of Denver means its column of air is not as high as in Milwaukee.
Since many snacks are sealed in pressurized bags, a bag sealed in Milwaukee requires higher internal pressure than one made in Denver. Thus a Milwaukee bag of snacks will expand when brought to the lower air pressure of Denver and could even explode.
Direction of fluid pressure
Now, what is different about pressure caused by a liquid, or gas is that not only is there pressure pushing down at a given point, but there is also the same pressure pushing up and to the sides.
All directions
The pressure is the same in all directions in a fluid at a given point. This is true because of the characteristic of liquids and gases to take the shape of their container.
Water pressure is the same in all directions
What this also means that any hollow container submersed in a liquid has pressure on every square inch of its surface, top and bottom.
Swimming under water
When you swim under water, the pressure of the water gets greater on your body, the deeper you get. Now, the question is: "Why aren't you crushed by all this weight?"
The reason is that your body compensates by creating an internal pressure that is equal to the air or water pressure. You are somewhat like a balloon filled with fluids under pressure. Now, when you go very deep under water, the water pressure may get greater than your body can compensate for, and you get uncomfortable.
Other pressure effects
Other effects of fluid pressure are motion, heating and chemical effects, as well as applications in the field of hydraulics and in aircraft.
(See Applications of Fluid Principles for details.)
Wind and current
The movement of a fluid, such as with wind or the current of a river can apply a pressure to an object in its way proportional to the surface area perpendicular to the direction of motion.
Streamlining the object reduces this pressure.
Heating and chemical effects
When you heat a fluid, it usually expands. If you heat a fluid that is in an enclosed container, the expansion will result in greater internal pressure. For example, heating a balloon will cause it to expand.
Likewise, chemical reactions that give off gases will increase the pressure inside the container. For example, shaking a carbonated drink bottle releases more gas and will result in greater internal pressure. This can be experienced when you open the bottle and the drink squirts all over.
Hydraulics
When a fluid—especially a liquid—is in a partially closed container, a force applied in one area can result in a greater force in another area. This effect is used in hydraulics to create a mechanical advantage by having the force applied to a small piston resulting in a greater force applied to large piston.
Aircraft
The scientist Bernoulli discovered that the air pressure in a tube goes down when the velocity of the air in the tube increases. This discovery became known as Bernoulli's Principle.
The greatest application of this principle is used in airplanes. The wing of an airplane is usually curved on top and flat on the bottom. When the air moves over the curved top portion of the wing, it speeds up because of the shape. This lowers the pressure with respect to the bottom part of the wing. Lower pressure on the top results in the lift required to keep the airplane aloft.
Summary
Fluid pressure from gravity is the weight of the fluid above divided by the area it is pushing on. Fluid pressure applies in all directions. Internal pressure of an object equals the external fluid pressure, otherwise the object could be crushed. Wind and heating can also create pressure.
Wednesday, July 23, 2014
Monday, July 21, 2014
engineers
Engineers are trained from the start to look at problems in different ways. They don’t just take the solution head on, but try to find the various ways and possibilities around it. They not only have been trained intensively with mathematics in order to strengthen their logic, but with many other science subjects. This allows them to analyze situations taking into consideration the different hazards and problems that could occur.
If an architect presents a group of engineers with a sketch or drawing; the engineers build what the architect asks for in the most feasible and safest way possible. When they eventually find a solution; they tend to solve it in steps. In doing so, this helps them amend or delete any unnecessary steps, making the process faster. It is an engineer’s job to look at the problem as a whole and try to solve it systematically. If solutions cannot be obtained, a compromise would be reached.
As an engineering student myself, I have seen the difference between school education and university education for engineers. Unlike school, where you were required to memorize most of the time, the engineering course requires you to understand and explain every aspect of a situation. Even when presented with a set of problems, we are trained to sum up all those problems into a single equation. There is also a lot more hands-on training where we get to experiment and test out different methods of finding solutions.
It is all due to the rigorous mental training that engineers have gone through. Many of today’s solutions have been further enhanced by the minds of engineers. This is proved by the amount of engineers employed in various non-engineering sectors, where they are required to design complicated working systems and plans. Without them some of the world’s greatest problems would not have solutions today.source:http://henri1471.blogspot.in/2009/01/how-do-engineers-think.html
Sunday, July 20, 2014
Friday, July 18, 2014
Wednesday, July 16, 2014
BEST PROFESSORS
Answer added to topic Indian Institutes of Technology.
Rukmini Bhaya Nair, one of India's most renowned poets and linguists, erstwhile HOD of Humanities Department, Visiting Faculty at Stanford University, Lexicographer. Ph.D from Cambridge.
Well, Ma'am's impeccable credentials and her inimitable charisma don't make her the best professor; but her wit, amiability and humility, which never allowed us to realize that the person teaching us was an international public figure, being good friends with the likes of Salman Rushdie, Vikram Seth and Gulzar.
I was fortunate to undertake the course titled 'Workshop in Creative Writing' by her and it was the only lecture, which was held at 8 o' clock in the morning, where I never missed a class.
For me, the most important virtue of any teacher is that the teacher should take keen interest in one's students' thinking process and should not consider them inferior to him/her. Nair Ma'am has been one such exceptional teacher, who listened to our thoughts with non-judgmental stance, read all our writings with immense interest as well as acceptance, and was considerate enough to acknowledge writings/arguments that were even moderately good. Despite the fact that she began the course with the first sentence, 'writing cannot be taught, but caught', she taught us writing better than whatever we had caught from all our past readings.
Some unique experiences:
Though now I wish that I had interacted more with her during my time at IIT, I can at least recommend anyone with a creative bent of mind to attend her course. You would learn a lot and realize that yes, there are amazing, though rare, professors in the campus who would shoo away every speck of sleep even if the class is at 8 am. FROM QUORA
Well, Ma'am's impeccable credentials and her inimitable charisma don't make her the best professor; but her wit, amiability and humility, which never allowed us to realize that the person teaching us was an international public figure, being good friends with the likes of Salman Rushdie, Vikram Seth and Gulzar.
I was fortunate to undertake the course titled 'Workshop in Creative Writing' by her and it was the only lecture, which was held at 8 o' clock in the morning, where I never missed a class.
For me, the most important virtue of any teacher is that the teacher should take keen interest in one's students' thinking process and should not consider them inferior to him/her. Nair Ma'am has been one such exceptional teacher, who listened to our thoughts with non-judgmental stance, read all our writings with immense interest as well as acceptance, and was considerate enough to acknowledge writings/arguments that were even moderately good. Despite the fact that she began the course with the first sentence, 'writing cannot be taught, but caught', she taught us writing better than whatever we had caught from all our past readings.
Some unique experiences:
- I remember the most unique exam that I had ever taken: where we were handed wooden elephant toys, all distinct, which we had to describe in words - so detailed that Ma'am should be able to identify which elephant out of those 60 we were talking about.
- Madam was very open to class participation, in truly international feel. While discussing poetry, a student suggested her to dissect a rock song. The next day, she brings forth and discusses a heavy metal song in the class.
- Our class projects, the assignment, that had 35% weightage had to be a long creative writing piece delving into a genre chosen from among 60 different kind of emotions like jealousy, love, anger, greed etc. that she had enlisted. It was one of the best exercises to polish writing skills, as it forced us to observe a particular emotion very keenly and bring that observation in practice.
- She made me understand the difference between sadism and schadenfreude. If you get robbed and I enjoy, it's not sadistic pleasure. It's schadenfreude. If I rob you and I enjoy, it's sadistic pleasure.
- Unlike other elite literary (pseudo-)intellectuals, Madam never took a cynical stand towards Chetan Bhagat, instead asked for our opinions, which quadrupled my respect for her. She presented us with a balanced view that Chetan Bhagat, despite not being a very brilliant writer, deserves great credit for evoking the reading spirit among youth and striking a chord with them with his simple language, which many brilliant writers couldn't.
- She had called her friends for a special lecture in our class. You know who her friends were: Sir Mark Tully, the eminent journalist; Ritu Menon, award winning publisher and Keki Daruwala, the well-known poet. She was also planning to call Gulzar Saheb into our early morning lecture, but unfortunately dates couldn't be finalized.
- I used to send her my stories every now and then, which she used to read and critique. I remember one of her suggestions, when I had sent her two of the love stories that I had written - one humorous (which I considered to be my best one) and another philosophical (which I thought was a little boring). She had liked the philosophical one more, saying that a good story is the one which makes one think, rather than laugh or cry.
- I remember during the course, my first novel had gotten published. Madam somehow had got to know about it; she summoned me and asked for my book. Fearing that she wouldn't be able to relate to it as it was a comedy of errors in the life of a student, I shyly said, "Ma'am, you wouldn't like it," to which she had replied, "You, being a writer, should never underestimate your own work". It was an uplifting feedback which has been etched in my memory ever since. I'm still to give her the book though. :P
Though now I wish that I had interacted more with her during my time at IIT, I can at least recommend anyone with a creative bent of mind to attend her course. You would learn a lot and realize that yes, there are amazing, though rare, professors in the campus who would shoo away every speck of sleep even if the class is at 8 am. FROM QUORA
VISCOSITY AND DENSITY
1.AS YOU GO IN A HIGH ALTITUDE THE DENSITY OF AIR DECREASES AND IT IS HARD TO BREATHE
2.VISCOSITY OF LIQUIDS DECREASES AS TEMPERATURE IS INCREASED
Tuesday, July 15, 2014
Sunday, July 6, 2014
Aerogel holds 15 entries in the Guinness Book of Records, more than any other material. Sometimes called “frozen smoke”, aerogel is made by the supercritical drying of liquid gels of alumina, chromia, tin oxide, or carbon. It’s 99.8% empty space, which makes it look semi-transparent. Aerogel is a fantastic insulator — if you had a shield of aerogel, you could easily defend yourself from a flamethrower. It stops cold, it stops heat. You could build a warm dome on the Moon. Aerogels have unbelievable surface area in their internal fractal structures — cubes of aerogel just an inch on a side may have an internal surface area equivalent to a football field. Despite its low density, aerogel has been looked into as a component of military armor because of its insulating properties.
This tiny block of transparent aerogel is supporting a brick weighing 2.5 kg. The aerogel’s density is 3 mg/cm3.
This tiny block of transparent aerogel is supporting a brick weighing 2.5 kg. The aerogel’s density is 3 mg/cm3.
STRESS AND STRAIN
STRESS: STRESS IS A PROPERTY OF A MATERIAL BY WHICH THE MATERIAL CAN
WITHSTAND THE EXTERNAL FORCE.IT IS DEFINED AS FORCE PER UNIT AREA.
STRAIN IS A PERCENTAGE VALUE WHICH DESCRIBES HOW MUCH PERCENTAGE THE MATERIAL IS CHANGED FROM ITS ORIGINAL DIMENSION
STRAIN IS A PERCENTAGE VALUE WHICH DESCRIBES HOW MUCH PERCENTAGE THE MATERIAL IS CHANGED FROM ITS ORIGINAL DIMENSION
Thursday, July 3, 2014
When children spend more time in structured activities, they get worse at working toward goals http://blogs.edweek.org/teachers/teaching_now/2014/07/study_too_many_structured_activities_hinder_childrens_executive_functioning.html … pic.twitter.com/z0sXc5kgpJ
Wednesday, July 2, 2014
thermodynamics 1st law....by professor karna
by...karna
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