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General and Special Relativity
Relativity is the theory stating that all measurements depend on the relative motions of the observer and the observed. The theories of general and specific relativity were both proposed by Albert Einstein.
813 Questions
Why did Albert Einstein invent the electromagnetic pump?
He didn't.
Einstein simply developed the theoretical basis that made optical pumping a goal to seek, in order to create a lasing action.
Can Superman travel back in time by flying round the earth backward?
It's tempting to ask what you mean by backward, but unnecessary. The answer is no. Backward time travel is not possible under any circumstances.
What did Albert Enstine get on his sats?
SAT wasn't invented yet when Einstein went to college. This question is just dumb.
Energy travels from your hand to the surface, because even the slightest touch transfers energy. Cold doesn't transfer from the surface to your hand, your nerves just tell your brain that the surface is cold.
How fast do plasma thrusters propel you?
That all depends on how long they're turned on. Their advantage is that they can run for a long time. They will not propel you very fast during short periods, but they will propel you very efficiently.
What did people think about theory of general relativity?
At first people thought that General Relativity was a bizarre and irrelevant theory. However, as time went by, people started to accept General Relativity more and more.
Why mass has energy or energy has mass?
The relation between mass and energy (E = mc^2) is a consequence of Einstein's theory of special relativity. This theory is based on the empirical fact that the speed of light is constant for any non-accelerating observer.
Why does this lead to an equivalence between mass and energy?
Well, let us consider a thought experiment. Imagine there is an object A which emits two photons (particles of light), one to the right, and one to the left. Both photons have an equal amount of energy (e.g. E/2). Because both photons have the same energy, they also have the same momentum and the total momentum in the frame remains the same (the total energy also remains the same since A has lost E through the emission).
Now imagine what this looks like for an observer in constant (non zero) motion. According to special relativity the photon traveling in his direction is blue-shifted, thus having an energy greater than E/2. The other photon is instead red-shifted, having an energy of less than E/2.
Of course the total amount of energy combined is still E. However, since the photons have unequal energy they also have unequal momentum. Object A however does not change his velocity during emission (remember that in the rest frame (where A is not moving) the photons were emitted with equal momentum in opposite directions), so now there is a net momentum gain in the direction of our moving observer!
But momentum must be conserved! How is this possible? The answer is that object A DID lose momentum (exactly enough to cancel the extra one), but since its velocity did not change it must have been its mass that has changed! (Remember that momentum equals mass times velocity at low energy).
Calculations then show that the amount of mass lost to A is equal to E/c^2. Hence the equation E = mc^2.
In a sense, then, mass and energy are related because the speed of light is a constant!
What gave Einstein the idea for the theory of realativity?
As he was riding on a bus, he ran through a thought experiment in which he traveled at faster and faster speeds away from a clock tower he had noticed out the back window.
Earth's gravitational force will have the greatest effect on an airplane?
The gravitational force between the Earth and an airplane is greatest when the
airplane is at the minimum possible altitude.
Its effect on the airplane depends on how the gravitational force is related to the
total system of forces on the aircraft, that is, what other forces are acting on it at
the same time, whether it's climbing, diving, standing still on level ground, standing
on sloped ground in a wind, etc.
What vegetables sink or float?
if the veggie grows underground, it will sink, and veggies that grow above ground, will float
Today my Kindergarten class made Stone Soup. We discovered that carrots floated and mushrooms sank - before cooking. After cooking all the vegetables floated. So the above statement is false. I would like to know why the potatoes and mushrooms sank at first and then floated after cooking.
Is density constant according to special theory of relativity?
Everything remains the same....I think
How is the moons orbit around the earth related to an apple falling from a tree?
because when an apple falls from a tree, it spins as it goes down to the ground.
That apple has fallen from a branch which launches it off to the ground giving it
energy. As it spins, the energy is still alive in it and once it stops spinning and hits
the floor, it will bounce and then that energy will be gone. The moon's orbit is
similar to that because the moon orbits around the Earth. The Earth is the branch
which is the reason why the moon orbits around the Earth. That's why we have
morning and night of course. So the Earth is the moon's branch and so the moon is
"falling" and spinning as it goes down. The moon revolves around the Earth and it
spins on its axis. That is how the moon's orbit around Earth is related to an apple
falling from a tree.
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Answer #2:
One is tempted to move the answer above into the category that deals with
the relationship between rainbows and unicorns, but I'll steadfastly resist it.
The falling apple and the orbiting moon are both responding in the same way to
the same force, and their motions are both perfectly explained and predicted by
the same deceptively simple formula for the gravitational force, presented by
Newton more than 250 years ago.
The branch, the spin of the apple, the ground, the floor, the bounce, the spin of
the moon, the spin of the Earth, morning, and night, are all enrolled in a school of
red herrings. None of them has anything to do with the question, or with its answer.
Yes but it would take a downward force. In a free fall scenario, an object reaches Terminal Velocity or 200 km/h. Obviously you can go faster if you have a rocket strapped to your back though.
Was Albert Einstein the first one to invent the laser?
Einstein did not invent a laser. His works in physics laid the foundation for the developement of the laser however.
Roll number of bed entrance exam2007-08?
neelam gangwar year 2007-8 bed entrance but my roll number miss
You want a conclusion about globalization?
Be where you want when you want. No more borders or communication problems.
Can you fly backwards around the earth and turn back time?
No, you can't. You probably saw in the movie how tough it was even for Superman.
And that was fiction ... made up ! ... and still he almost couldn't do it.
it depends: if the fly is stopping a train the size of a period or if the fly is
trying to stop a 10-ton train.
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Actually it would seem that a fly traveling exactly opposite to the
direction of a moving 10-ton train and colliding with it would have the
effect of stopping the train dead still...at least for a micro-milli-second.
Consider the velocity of the fly relative to the track. It is intuitive that upon
impact, the fly's velocity accelerates to zero and then accelerates in the
opposite direction to match the velocity of the train.
But if it is at the moment of impact of the fly and the train when the fly's
velocity relative to the track is zero...and since the fly is in contact with the
train at that instant of impact...then the velocity of the train relative to the
track must also be zero. Right?
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I don't think so, if we're talking about a train moving at speeds we'd
consider normal:
The train stops the fly for a micro second before the fly reverses direction,
that's true, and perhaps the fly's momentum slows a portion of the train
directly in contact with the fly in an elastic-like collision (forming a
molecular-sized temporary indentation). But the bulk of the forces of the
collision are borne by the fly, who's body is deformed and splattered by the
rapid change in direction.
However, a fly can stop a train, if the fly's momentum is equal to or greater
than that of the train: e.g. if the train's velocity is so small that it's momentum
is less than that of the fly flying directly at it. This would be a train moving so
slowly it would be imperceptible to us.
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Relatively-Useless Contribution #4:
If the train is under power, then the answer is a big fat undebatable 'no',
because the train's engines deliver more power than the fly can ever match.
But if the train is coasting, then the fly simply needs to apply a constant force
against the front of the locomotive, and keep applying it until the product of
(the force applied) x (the distance the train rolls while the force is applied)
is equal to the kinetic energy the train had when the fly arrived. Nothing to it.
What does the E represent in Einstein's equation E equals mc2?
Energy.
The equation says that the quantity of Energy (E) equivalent to some quantity of mass
is equal to m times c2 (c squared).
'm' is the quantity of mass, and 'c' is the speed of light.
The actual numbers are incredible. The equation says that a mass that weighs about 2.2 pounds is equivalent to 25 billion kilowatt-hours of energy ... about 500 days' worth of the total generating capacity of the Zion nuclear power plant north of Chicago. This energy would be released completely only by reducing the mass to its constituent particles and then annihilating them all. Nuclear reactors release only a tiny fraction of the available energy in their nuclear fuel.
C is equal to about 300,000 kilometers/second. Squared it is 9 x 1010 (90 billion).
How do you find the momentum of an electron when it is moving with a speed of 0.75c?
The momentum in special relativity is given by the following formula:
p = gamma*m*c^2
where c is the speed of light, m is the mass of (in this case) the electron and gamma is the so-called gamma factor, which is:
gamma = 1/sqrt(1-(v/c)^2)
where v is the speed of the electron.
Using v = 0.75c we have for gamma:
gamma = 1/sqrt(1-0.75^2)
which is about 1.5.
Thus we have:
p = 1.5*m*c^2.
Can you break down the parts of Einstein's Theory of General Relativity?
We know that einstein theory of general relativity is composed of different parts,but they are all related.If we break down into parts it will not have true sense or meaning.The different parts are all needed to help each other.Its more like an egg.There is the shell,the white part and the yolk.They are all part of an egg but we can never say that only the yolk or the shell or the white part is the egg.Both the shell and the yolk also cannot be said as a true egg.Only when the shell,the white part and the yolk are in combination it is a true egg.Just like that relativity is also a single theory made of different parts.So relativity cannot be break down into parts.When all the parts are combined we have one brilliant theory.RELATIVITY.
