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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
How can two objects with different speeds move in the same amount of time?
Two objects with different speeds can cover different distances in the same amount of time if they start at different locations. For example, one object may start closer to the finish line, allowing it to cover a shorter distance in the same amount of time as the object moving at a faster speed.
What speed must a particle move for its mass to double?
M = M0 / sqrt( 1 - v2/c2 )
If M = 2M0 then
sqrt( 1 - v2/c2 ) = 0.5
( 1 - v2/c2 ) = 0.25
1 - 0.25 = 0.75 = v2/c2
v2 = 0.75 c2
v = sqrt(0.75) c = 0.866 c = 259,627,885 meters (161,325 miles) per second
What is the definition of time according to Einstein?
According to Einstein's theory of relativity, time is not absolute but instead is relative and can be experienced differently depending on an observer's relative motion and gravitational field. This theory suggests that time is intertwined with space in a four-dimensional spacetime continuum.
When the Earth is closer to the Sun it is in a slightly stronger gravitational field.
According to "General Relativity" this means time will be slowed down compared with when it's further away. However, the effect will be very small.
There is another small effect because the Earth orbits faster when closer to the Sun. This is part of "Special Relativity". Again the effect is to slow down time relative to when the Earth is further from the Sun.
Any gravity well will "slow down" time, just not perceptible for those in the well. Without getting too technical, space and time are essentially the same, or are at least interwoven. Gravity warps this fabric.
An easier way to imagine this is to think in terms of a black hole. As light and matter fall into the gravity well of a black hole, time will slow. Picture a space ship falling into the gravity well. The astronaut inside the ship will perceive the passage of time normally, all the way to the event horizon. If the ship is able to somehow stop and orbit at this point, time for the astronaut will appear unchanged. But, to an observer outside the gravity well, the astronaut will appear to move more slowly, as if time is slowing down the closer the ship gets to the event horizon.
The gravity wells of Earth and the Sun are similar to that of a black hole, just nowhere near as intense.
For further information, study the relativistic affects of gravity. Space and time here limit how much this can be discussed. (No pun intended. Or, is there?)
What is person called who repairs punctures?
A person who repairs punctures is commonly called a tire repair technician or a puncture repair specialist.
How has the theory of relativity affected us today?
The theory of relativity, proposed by Albert Einstein, has had a profound impact on our understanding of the nature of time, space, and energy. It has led to advancements in technology such as GPS systems, nuclear power, and particle accelerators. Additionally, the theory has influenced fields such as cosmology and astrophysics, shaping our understanding of the universe.
Temporal variability refers to changes over time in a specific variable or phenomenon. It captures the fluctuations and variations that occur in a system or dataset across different time intervals. Understanding temporal variability is essential in analyzing trends, patterns, and dynamics that may exist in a time series data.
The effective mass of a hole is a concept used in solid-state physics to describe the behavior of a hole in a crystal lattice. It represents the mass of an electron in the context of hole motion and is typically expressed as a positive value equal to the negative of the electron's mass. It is an important parameter for understanding the electrical and optical properties of semiconductors.
The speed of light is 2.997925 x 108m/s, so 2.997925 x 105km/s
How do you know a substance will float?
If a certain volume of something (like a beach ball) was the same as a certain amount of water(water the size of the beach ball), but it weighs less, than it will float. An ordinary marble weighs a lot for it's tiny size, and in that case it will CERTAINLY sink in water.
Everything that I said about an amount of something weighing a certain amount of g/kgs/tonnes, is called 'Density', like planet Saturn. This planet is the densiest and CAN float on water if it could...
The only thing that matters is the RELATIVE Velocity between the two Objects, not whether they are BOTH moving or not. If one is standing still and the other going 100 MPH, the result is the same as if both were going 50 MPH.
What is the Specific gravity of grease?
The specific gravity of grease typically ranges from 0.85 to 1.05, depending on the composition and consistency of the grease. Grease with a higher specific gravity tends to be denser and may contain more solid components.
How can a normal person apply the equation 'E equals mc squared'?
First of all, there is no basis for the implication that the people who use that equation
in their daily life and work may be in some sense 'abnormal'.
No human being living a typical life on planet Earth has any need to understand or apply [ E = mc2 ]
in order to pursue a career, live a full life, or make sense of his daily experiences. This may well be
the main reason that the equation was unknown, and generally unmissed, before the 20th Century.
Is the speed of light the same in any material?
The speed of light (c) in a vacuum, is exactly299,792,458 meters per second (ms-1), which rounds up very nicely to 300,000,000 ms-1, which scientists write as 3 x 108 ms-1.
In more dense media the speed is slower,
e.g. # Air, only slightly less than c, speed is 0.9997 of c. # water 0.75 of c. # fused quartz 0.686 of c. # crown glass* 0.658 of c. # dense flint glass* 0.60 of c. # diamond, approx 0.41 of c. CALCULATIONS The speed of light, using a very close approximation for calculation purposes, is taken as 3.0 x 108 m/s (metres per second). i.e. 300,000,000 m/s The greater the refractive index of the medium, the slower the speed of light in that medium/material. The speed of light in a vacuum [c] divided by the velocity of light in the material [v] equals the refractive index [n] of the material. Examples 1. calculate the refractive index of space: c/c equals 1 2. water (the speed of light in water is 225,056,264 m/s): c/ 225056264 equals 1.333 Inversely, if we know the refractive index of a material, we can calculate the velocity of light through that material, i.e. the speed of light [c] divided by the refractive index [n] equals the velocity of light [v] in that material Using the example of water, refractive index 1.333 :- 300,000,000 [c] divided by 1.333 [n] equals 225,056,264 [n] i.e. the velocity of light in water is 225,056,264 m/s. This is 225,056,264/300,000,000 ths the speed of light, or 0.75 of c. SOME REFRACTIVE INDICES * vacuum1.00 * air 1.0003 * water 1.333 * fused quartz 1.4585 * plexiglass 1.51 * crown glass* 1.52 * diamond 2.417 * gallium phosphide 3.50 *Crown glass is a type of glass used in lenses, and has a lower refractive index than flint glass which is also used in lenses. For more information, see Related Links below this box
The increase in the rate of expansion of the universe does not directly cause everything to get warmer. It leads to a decrease in the density of matter and energy in the universe, which can have temperature implications for certain systems over vast cosmic timescales. Additionally, time dilation does not cause things to become warmer - it affects the perception of time passing based on relative motion or gravity but does not directly impact temperature.
- electromagnetic - long range, either attractive or repulsive, moderate
- weak nuclear - short range, either attractive or repulsive, weak
- strong nuclear - very short range, either attractive or repulsive, very strong
- gravity - long range, always attractive, very weak
He is incorrect. Newton's 3rd law states that any force has an equal and opposite force. This means he pushes back on the water with the oars (normal), and this creates a forward normal force on the oars pushing the oars and the boat forward.
sqrt( 1 - v2/c2 ) = 0.5
1 - v2/c2 = 0.25
v2/c2 = 0.75
v/c = sqrt(0.75) = 0.86603
v = 0.86603 c = 259,627.9 kilometers per second = 161,324.9 miles per second.
Mass does not affect time directly. However, according to the theory of relativity, massive objects can bend space-time, causing time to move differently in their presence. This effect, known as gravitational time dilation, means that time runs slower in stronger gravitational fields.
What forces are acting on a book that is lying on a table?
Gravitational force (weight), pointing down.
Reaction force, equal to the gravitational force (weight), exerted by the tabletop, pointing up.
What is the statement of time dilation by Einstein?
In a broad sense it means that you see clocks carried by people moving relative to you move slowly. This effect is totally negligible in every day life by the way, the speeds need to approach that of light for the effects to be apparent.
More specifically it states that time moves slower in inertial frames moving relative to yours.
Which colours have the fastest speed?
In terms of how our eyes perceive them, red light has the longest wavelength and bends the least, so it travels faster than other colors in a vacuum. However, when light passes through a medium like air or glass, the speed may vary depending on the color's interaction with the medium.
Why does an object's mass increase as its velocity increases?
To answer why delves into philosophy or theology. Why is there gravity - there just is.
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The relativistic mass is the mass an object possesses because it travels at speeds that approach the speed of light ('c'). According to the Lorentz factor, the relativistic mass of an object increases as an object's speed approaches c as follows:
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mrel = m / (1 - v2/c2)1/2
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where:
- mrel is the relativistic mass
- m is the rest mass
- v is the object's velocity
- c is the speed of light
Relativistic mass is only significantly greater than rest mass for objects travelling faster than 0.1c, or one tenth the speed of light, or about 108,000,000 KPH (67,000,000 MPH). As you can see from the above equation, the denominator approaches zero as the object's velocity approaches the speed of light, making the relativistic mass unbounded.
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The Lorentz factor also applies to an object's momentum and its energy. This means not only the mass, but also an object's momentum and energy approach infinity as the object's speed approaches c. Note that, in this context, an object's rest energy is in according to the equation:
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E = mc2
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and this energy increases as the object's speed approaches c.
Does reflection from an irregular surface obey the law of refraction?
Yes. The angle of reflection = the angle of incidence. This is where pictures of ray traces (see the link below) come in very handy, keeping in mind that a ray trace is a very small (the magical physics *very small*) portion of the light that is falling on the mirror at a very small period of time. It works easiest for curved mirrors if the mirror has the reflective surface on the front (where the light is coming from) so we don't have to play with the refractive equations of the intermediate media. The mathematics of the angle of incidence and reflection is fairly easy for linear equation surfaces, like shperical, parabolic and hyperbolic, but gets a little more involved for nonlinear surfaces (like wrinkled tin foil).
How does relativity affect weight?
In the theory of relativity, weight depends on the gravitational field in which an object is located. In the presence of a strong gravitational field, such as near a massive body like a planet or a star, weight can vary due to the curvature of spacetime. This effect is described by Einstein's general theory of relativity.
