Cartoon Law I
Any body suspended in space will remain in space until made aware of its situation.
Daffy Duck steps off a cliff, expecting further pastureland. He loiters in midair, soliloquizing flippantly, until he chances to look down. At this point, the familiar principle of 32 feet per second per second takes over.
Cartoon Law II
Any body in motion will tend to remain in motion until solid matter intervenes suddenly.
Whether shot from a cannon or in hot pursuit on foot, cartoon characters are so absolute in their momentum that only a telephone pole or an outsize boulder retards their forward motion absolutely. Sir Isaac Newton called this sudden termination of motion the stooge’s surcease.
Cartoon Law III
Any body passing through solid matter will leave a perforation conforming to its perimeter.
Also called the silhouette of passage, this phenomenon is the specialty of victims of directed-pressure explosions and of reckless cowards who are so eager to escape that they exit directly through the wall of a house, leaving a cookie-cutout-perfect hole. The threat of skunks or matrimony often catalyzes this reaction.
Cartoon Law IV
The time required for an object to fall twenty stories is greater than or equal to the time it takes for whoever knocked it off the ledge to spiral down twenty flights to attempt to capture it unbroken.
Such an object is inevitably priceless, the attempt to capture it inevitably unsuccessful.
Cartoon Law V
All principles of gravity are negated by fear.
Psychic forces are sufficient in most bodies for a shock to propel them directly away from the earth’s surface. A spooky noise or an adversary’s signature sound will induce motion upward, usually to the cradle of a chandelier, a treetop, or the crest of a flagpole. The feet of a character who is running or the wheels of a speeding auto need never touch the ground, especially when in flight.
Cartoon Law VI
As speed increases, objects can be in several places at once.
This is particularly true of tooth-and-claw fights, in which a character’s head may be glimpsed emerging from the cloud of altercation at several places simultaneously. This effect is common as well among bodies that are spinning or being throttled. A ‘wacky’ character has the option of self- replication only at manic high speeds and may ricochet off walls to achieve the velocity required.
Cartoon Law VII
Certain bodies can pass through solid walls painted to resemble tunnel entrances; others cannot.
This trompe l’oeil inconsistency has baffled generations, but at least it is known that whoever paints an entrance on a wall’s surface to trick an opponent will be unable to pursue him into this theoretical space. The painter is flattened against the wall when he attempts to follow into the painting. This is ultimately a problem of art, not of science.
Cartoon Law VIII
Any violent rearrangement of feline matter is impermanent.
Cartoon cats possess even more deaths than the traditional nine lives might comfortably afford. They can be decimated, spliced, splayed, accordion- pleated, spindled, or disassembled, but they cannot be destroyed. After a few moments of blinking self pity, they reinflate, elongate, snap back, or solidify.
Corollary: A cat will assume the shape of its container.
Cartoon Law IX
Everything falls faster than an anvil.
Cartoon Law X
For every vengeance there is an equal and opposite revengeance.
This is the one law of animated cartoon motion that also applies to the physical world at large. For that reason, we need the relief of watching it happen to a duck instead.
AMENDMENTS TO THE CARTOON LAWS OF PHYSICS
Cartoon Law Amendment A
A sharp object will always propel a character upward.
When poked (usually in the buttocks) with a sharp object (usually a pin), a character will defy gravity by shooting straight up, with great velocity.
Cartoon Law Amendment B
The laws of object permanence are nullified for "cool" characters.
Characters who are intended to be "cool" can make previously nonexistent objects appear from behind their backs at will. For instance, the Road Runner can materialize signs to express himself without speaking.
Cartoon Law Amendment C
Explosive weapons cannot cause fatal injuries.
They merely turn characters temporarily black and smoky.
Cartoon Law Amendment D
Gravity is transmitted by slow-moving waves of large wavelengths.
Their operation can be witnessed by observing the behavior of a canine suspended over a large vertical drop. Its feet will begin to fall first, causing its legs to stretch. As the wave reaches its torso, that part will begin to fall, causing the neck to stretch. As the head begins to fall, tension is released and the canine will resume its regular proportions until such time as it strikes the ground.
Cartoon Law Amendment E
Dynamite is spontaneously generated in "C-spaces" (spaces in which Cartoon laws hold).
The process is analogous to steady-state theories of the universe which postulated that the tensions involved in maintaining a space would cause the creation of hydrogen from nothing. Dynamite quanta are quite large (stick-sized) and unstable (lit). Such quanta are attracted to psychic forces generated by feelings of distress in "cool" characters (see Amendment B, which may be a special case of this law), who are able to use said quanta to their advantage. One may imagine C-spaces where all matter and energy result from primal masses of dynamite exploding. A big bang indeed.
By anisha
Published: 5/28/2002
Thursday, February 12, 2009
Einstein's observation on gravity proved right
"The speed of gravity matches the speed of light." This theory by Albert Einstein has finally been validated by astronomers who calculated and measured fundamental forces of nature with the help of a rare planetary alignment. Einstein, who formulated the basic theories about space, time and relativity, had assumed that gravity moved with the speed of light,(about 300,000 km per second).However until now, no attempts were made to prove this theory with actual physical measurement.
Gravity shapes the structures and evolution of stars, galaxies and the entire universe. The trajectories of bodies in the solar system are determined by the laws of gravity, while on earth all bodies have a weight, or downward force of gravity, proportional to their mass, which the Earth's mass exerts on them. Gravity is measured by the acceleration that it gives to freely falling objects. At the Earth's surface the acceleration of gravity is about 9.8 metres per second square. Thus, for every second, an object is in free fall, its speed increases by about 9.8 metres per second.
The work of Isaac Newton and Albert Einstein dominate the development of gravitational theory. Einstein's career was very interesting. In 1905, he published four papers - Brownian motion; the photoelectric effect; finding the size of molecules and relativity in a German Physics monthly. In 1914, he moved to Berlin, the Prussian Academy of Sciences. In 1916, he published the general theory of relativity in Annalen der Physik. In 1919, the Royal society of London verified the predictions made in Einstein's general theory of relativity. In 1921, he won the Noble prize for physics for the photoelectric law and work in the field of theoretical physics. In 1933, he renounced German citizenship and moved to U.S.A. Later, he accepted a full time position as a foundation member of the school of mathematics at the new Institute for advanced study in Princeton, New Jersey. In 1939, he wrote to President F.D.Roosevelt urging "watchfulness and if necessary, quick action" in atomic bomb research, marking the beginning of Manhattan Project.
Newton's classical theory of gravitational force held sway from his Principia, published in 1687, until Einstein's work in the early 20th century. The major significance of Einstein's theory is its radical conceptual departure from classical theory and its implications for further growth in physical thought.
Scientists Edward B. Fomalout of the National Radio Astronomy observatory and Sergei Kopeikain of the University of Missouri took up the task of measuring the velocity of gravity with the help of planet Jupiter. They measured the apparent change in the position of a distant quasar when its radio waves passed by Jupiter and were deflected by the gravitational field of the planet. The final calculation proved that gravity does indeed travel at the speed of light. The specific position of Jupiter that enables this particular measurement occurs only once a decade.
By Dhananjay Kulkarni
Published: 3/9/2004
Gravity shapes the structures and evolution of stars, galaxies and the entire universe. The trajectories of bodies in the solar system are determined by the laws of gravity, while on earth all bodies have a weight, or downward force of gravity, proportional to their mass, which the Earth's mass exerts on them. Gravity is measured by the acceleration that it gives to freely falling objects. At the Earth's surface the acceleration of gravity is about 9.8 metres per second square. Thus, for every second, an object is in free fall, its speed increases by about 9.8 metres per second.
The work of Isaac Newton and Albert Einstein dominate the development of gravitational theory. Einstein's career was very interesting. In 1905, he published four papers - Brownian motion; the photoelectric effect; finding the size of molecules and relativity in a German Physics monthly. In 1914, he moved to Berlin, the Prussian Academy of Sciences. In 1916, he published the general theory of relativity in Annalen der Physik. In 1919, the Royal society of London verified the predictions made in Einstein's general theory of relativity. In 1921, he won the Noble prize for physics for the photoelectric law and work in the field of theoretical physics. In 1933, he renounced German citizenship and moved to U.S.A. Later, he accepted a full time position as a foundation member of the school of mathematics at the new Institute for advanced study in Princeton, New Jersey. In 1939, he wrote to President F.D.Roosevelt urging "watchfulness and if necessary, quick action" in atomic bomb research, marking the beginning of Manhattan Project.
Newton's classical theory of gravitational force held sway from his Principia, published in 1687, until Einstein's work in the early 20th century. The major significance of Einstein's theory is its radical conceptual departure from classical theory and its implications for further growth in physical thought.
Scientists Edward B. Fomalout of the National Radio Astronomy observatory and Sergei Kopeikain of the University of Missouri took up the task of measuring the velocity of gravity with the help of planet Jupiter. They measured the apparent change in the position of a distant quasar when its radio waves passed by Jupiter and were deflected by the gravitational field of the planet. The final calculation proved that gravity does indeed travel at the speed of light. The specific position of Jupiter that enables this particular measurement occurs only once a decade.
By Dhananjay Kulkarni
Published: 3/9/2004
Einstein Fridge Comes in From the Cold
He is best known as the past century's most famous genius. But as well as devising the theory of relativity, Albert Einstein was also responsible, it emerged yesterday, for a less celebrated discovery - a fridge.
Nearly 80 years after he invented it, a group of German physicists have begun making Einstein's unique alcohol-powered fridge.
The existence of the fridge shows that the great scientist was not only a theoretician but also a down-to-earth practical inventor.
Jürgen Renn, director of the Max-Plank Institute in Berlin, said: "He came from a merchant family, he had to worry about money, and he was supposed to take over the family business."
Einstein wrote his theory of relativity in 1905, while working in the Swiss patent office. It was not until 1926, when he was living in Berlin and had won the Nobel prize, that he came up with his fridge.
He invented it after reading a news report about how an ordinary fridge had poisoned a sleeping Berlin family. Its pump had leaked sulphur dioxide.
Together with his fellow physicist Leo Szilard, Einstein built a fridge that used harmless alcohol gas.
Although Einstein took the trouble to patent his design, new technology meant his model never went into production. The only prototype built vanished. Only a handful of photographs exist.
The historian Peter Galison told the German science magazine ZeitWissen yesterday: "As a young man Einstein corresponded with friends about helicopters and measuring equipment, tinkered with small experiments, and filed patents."
Germany is gearing up for a double Einstein celebration next year. Events are planned to mark the centenary of his theory of relativity and the 50th anniversary of his death.
© Guardian News & Media 2008
Published: 12/1/2004
Nearly 80 years after he invented it, a group of German physicists have begun making Einstein's unique alcohol-powered fridge.
The existence of the fridge shows that the great scientist was not only a theoretician but also a down-to-earth practical inventor.
Jürgen Renn, director of the Max-Plank Institute in Berlin, said: "He came from a merchant family, he had to worry about money, and he was supposed to take over the family business."
Einstein wrote his theory of relativity in 1905, while working in the Swiss patent office. It was not until 1926, when he was living in Berlin and had won the Nobel prize, that he came up with his fridge.
He invented it after reading a news report about how an ordinary fridge had poisoned a sleeping Berlin family. Its pump had leaked sulphur dioxide.
Together with his fellow physicist Leo Szilard, Einstein built a fridge that used harmless alcohol gas.
Although Einstein took the trouble to patent his design, new technology meant his model never went into production. The only prototype built vanished. Only a handful of photographs exist.
The historian Peter Galison told the German science magazine ZeitWissen yesterday: "As a young man Einstein corresponded with friends about helicopters and measuring equipment, tinkered with small experiments, and filed patents."
Germany is gearing up for a double Einstein celebration next year. Events are planned to mark the centenary of his theory of relativity and the 50th anniversary of his death.
© Guardian News & Media 2008
Published: 12/1/2004
Tuesday, February 10, 2009
Thousands of video lectures from the world's top scholars
http://www.academicearth.org/
check the physic section
Force - an action which tends to cause a change in motion. A push or pull.
Forces come in two basic flavors; contact forces and field forces.
Contact forces occur as the name implies - when contact between two object is present. You cannot push your book across the table without contacting the book. A tennis racket cannot change the motion of the ball unless it contacts the ball.
Until a few years ago scientists believed that all forces could be categorized into five classes:
Gravitational force - the force of attraction between any two objects with mass.
Electric force - a force of attraction or repulsion between charged objects.
Magnetic force - a force of attraction or repulsion between ferro magnetic objects.
Strong force - the force holding protons and neutrons together in the nucleus.
Weak force - the force which causes radioactive decay.
In recent years it has been shown that the magnetic, strong, and weak forces are all variations of the electric force now called the electro-weak force. Many scientists believe that the gravitational force may also have an electromagnetic base, but no proof exists as of now.
This means that all forces, whether they are contact forces or field forces, are either a form of electrical force or gravitational force. When you push your book across the table it is the electrons in the atoms of your skin which are repelling the electrons in the atoms of the book. If you think contact is "actually touching" then you never really touch the book. The effect is the same no matter how you define it.
Force tends to cause a change in motion of an object. The definition of a force is an operational definition; it is defined by what it does. Remember that changes in motion are measured as acceleration. Forces tend to cause acceleration.
The unit of measurement of force is the Pound (lb) in the English system and the Newton (N) in the metric system. You are most familiar with pounds, like the measurement of your weight. Newtons will be new for you.
To get an idea of the size of a Newton, one Pound is the same force as 4.45 Newtons. Roughly speaking a Newton is a quarter Pound. A 100 lb person would weigh 445 N. That's one reason we don't use the metric system to express weight. No one wants to weigh 445 of anything.
Notice that the phrase "tends to cause" has been used because, as you will see later, a single force may not cause a change. It is only when the total of all the forces acting on an object has a non-zero value that the object will change its motion.
Now here's an interesting fact. Forces never operate alone. They always occur in pairs. Isaac Newton stated this as one of his basic laws back in the 1600's. We often refer to these two forces as action/reaction forces. You can't tell which is the action and which the reaction, but it doesn't make any difference.
Simply stated I can not push on you without you pushing back on me. Our pushes are the same size (magnitude) , bit they are in opposite directions. I push on you. You push on me.
If you throw a ball against the wall the ball pushes on the wall, and at the same time, the wall pushes on the ball. The wall pushes on the ball with the same amount of force that the ball pushes on the wall. One of the forces is on the ball, the other force is on the wall.
This is one of the most difficult concepts for students to accept.
Think of this example: A small car has a head on collision with a large truck. Does the car get "hit harder" than the truck?
Your first inclination would be to say "yes, the truck hits the car harder than the car hits the truck". Guess again. There is no doubt that the car will have more damage than the truck, that the people in the car may suffer more injuries than for those people in the truck, but it is not because the car gets "hit harder". As we will see in the next unit, the reason for the inequity in the collision is due to the smaller mass of the car. They both hit each other with the same force.
When a golf club hits a ball, the force of the club on the ball is the same amount of force the ball exerts on the club.
When a big senior runs into a small freshman in the hall the force of the senior on the freshman is the same as the force of the freshman on the senior.
When you stub your toe on a table leg the force of your toe on the table is the same force as the table on your toe.
Think about it, let it sink in. Whether you believe it or not, it's true.
concept of energy
Reduced to simplest terms, the universe is nothing more than a series of energy exchanges. As in much of physics, the concept of energy is easy to understand, but difficult to express and work with.
Energy = The ability to cause change.
Notice the simplicity of this definition. If something has the ability to cause a change in the physical or chemical properties of another object it has energy. If we restrict our study to mechanical energy, then we consider the changes in the state of motion of an object.
There are different classifications of energy, usually named for the source of the force involved; mechanical, gravitational, electrical, nuclear, etc. Within each of these areas the energy is further classified as either potential or kinetic energy.
Potential energy - Energy due to an object’s position.
Energy = The ability to cause change.
Notice the simplicity of this definition. If something has the ability to cause a change in the physical or chemical properties of another object it has energy. If we restrict our study to mechanical energy, then we consider the changes in the state of motion of an object.
There are different classifications of energy, usually named for the source of the force involved; mechanical, gravitational, electrical, nuclear, etc. Within each of these areas the energy is further classified as either potential or kinetic energy.
Potential energy - Energy due to an object’s position.
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