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# What is the escape speed of a black hole?

2023-01-23 12:58Physics
Summary: Today is 2023-01-23. Let me tell you about the escape speed of black holes. The text will begin right away. How many kilometers does a black hole run in a second The speed of a black hole is usually 1
Today is 2023-01-23. Let me tell you about the escape speed of black holes. The text will begin right away. How many kilometers does a black hole run in a second The speed of a black hole is usually 180000 kilometers per second. A black hole (English: black hole) is a region where the gravitational pull of space-time is so strong that all particles, even electromagnetic radiation such as light, cannot escape. General relativity predicts that mass close enough can distort space-time and form a black hole; the boundary from which it is impossible to escape is called the event horizon (English: event horizon). Although the event horizon has a significant impact on the fate and conditions of objects passing through it, observations of the area do not seem to detect any features. In many ways, a black hole is like an ideal blackbody. It does not reflect light. The first person who predicted the existence of black holes was the English Reverend John Mitchell. In a letter to Henry Cavendish (read on November 27, 1783, published the following year in the Journal of the Natural Science Society), he put forward the idea of celestial bodies so massive that even light could not escape. Assuming that the density of such a celestial body is the same as that of the sun, Michelle concluded by simple calculation that such a celestial body will form when its diameter is more than 500 times the diameter of the sun and its surface escape velocity will exceed the speed of light. Michelle rightly pointed out that such super-massive but non-radioactive objects can be observed through their gravitational effects on nearby visible objects. Scholars at the time were very interested in the suggestion of giant but invisible stars hidden in view, but enthusiasm waned when the wave theory of light prevailed over the theory of particles in the 19th century. Because if light is a wave rather than a quot; particle & quot;, it is not clear about the effect of gravity on escaping light waves. Is the escape velocity of the black hole 1.13c? The escape velocity at the edge of the event horizon of the black hole is 1c, the greater the escape velocity is, and the escape velocity of the singularity is infinite. What are the first, second and third speeds of the universe, respectively, based on what to escape? Cosmic speed: the minimum speed required for a spacecraft launched from the earth's surface to orbit the earth, escape gravity, or fly out of the solar system. The speed that can circle the earth in the lowest circular orbit is called the first cosmic speed, which is about 7.9 km / s; the minimum speed to escape from the earth's gravity is called the second cosmic speed, which is about 11.2 km / s; and the minimum speed that flies out of the solar system is called the third cosmic speed, about 16. 7 km / s. The first cosmic velocity (also known as circumferential velocity): the speed at which an object moves in a circle close to the surface of the earth. The second cosmic velocity (also known as detachment velocity): the minimum initial velocity required for an object to fly away from the earth completely free of the shackles of the earth's gravity. The third cosmic velocity (also known as escape velocity): the minimum initial velocity required for an object launched on the earth to escape the sun's gravitational shackles and fly out of the solar system. Its size is 16. 7 km / s. Orbit velocity and escape velocity can also be applied to other celestial bodies. For example, to calculate the orbiting velocity and escape velocity of Mars, you only need to replace the M _ ~ R _ (g) in the formula with the mass, radius and su rface gravity acceleration of Mars. The determining factor the escape velocity depends on the mass of the planet. If a planet has a large mass, its gravity is strong and its escape velocity is high. On the other hand, a lighter planet will have a smaller escape velocity. The escape velocity also depends on the distance between the object and the center of the planet. The closer the distance is, the greater the escape velocity is. The escape velocity of the earth is 11.2km / s and that of the sun is 617.7 km / s. If the mass and surface gravity of a celestial body is so strong that the escape velocity reaches or even exceeds the speed of light, the celestial body is a black hole. The escape velocity of a black hole is 300000 km / s. It is generally believed that the universe has no boundaries, and there is no point in saying that matter in the universe escapes to other places, so it seems meaningless to say that the escape velocity of the universe. The above reference:-the second cosmic speed Calculation method of escape velocity If an object with a mass of m has a velocity v, its kinetic energy is MV ^ 2 / 2. Suppose that the gravitational potential energy at infinity is zero (it should be zero gravitational potential energy when an object is infinitely far from the earth, so this assumption is reasonable). Then the potential energy of an object with a distance from the earth is-mar (an is the gravitational acceleration of the object at this point, and the minus sign indicates that the potential energy of the object is less than that of infinity). And because the earth's gravitational force on an object can be regarded as the weight of an object, there is GmM/r2=ma, that is, a = (GM) / R2. So the potential ener gy of the object can be written as-GmM/r, where M is the mass of the earth. If the velocity of the body on the ground is V and the radius of the earth is R, according to the law of conservation of energy, the sum of kinetic energy and potential energy on the earth surface is equal to the sum of kinetic energy and potential energy at r, that is, mV2/2+ (- GMm/R) = mv2/2+ (- GmM/r). When an object gets rid of the earth's gravity, r can be regarded as infinite, and the gravitational potential energy is zero, then the above equation becomes mV2/2-GmM/R=mv2/2. Obviously, when v equals 00:00, the required detachment velocity V is the minimum, that is, the V=2GM/R root sign, and because of GMm/R2=mg, the V=2gR root sign. In addition, the detachment velocity (the second cosmic speed) is exactly twice the root sign of the first cosmic speed. Where g is the gravitational acceleration of the earth's surface, which is 9.8 newtons / kg. The radius of the earth is about 6370 km, resulting in an escape velocity of 11.17km / s. Different celestial bodies have different escape velocities, and the formula of departure velocity is also applicable to other celestial bodies. The escape velocity of extended data depends on the mass of the planet. If a planet has a large mass, its gravity is strong and its escape velocity is large. On the other hand, a lighter planet will have a smaller escape velocity. The escape velocity also depends on the distance between the object and the center of the planet. the closer the distance is, the greater the escape velocity is. If the mass and surface gravity of a celestial body is so strong that the escape velocity reaches or even exceeds the speed of light, the celestial body is a black hole. The escape velocity of a black hole is 300000 km / s. It is generally believed that the universe has no boundaries, and there is no point in saying that matter in the universe escapes to other places. Therefore, it seems pointless to discuss the escape velocity of the universe. The second cosmic speed is the minimum speed required for man-made celestial bodies to break free from the gravitational shackles of the earth. When the speed of the object reaches 11.2 km / s, it can get rid of the shackles of the earth's gravity and fly away from the earth into the orbit around the sun, no longer around the earth. The minimum velocity away from the earth's gravity is the second cosmic speed. The initial flight speed of all kinds of planetary probes is higher than the second cosmic speed. The second cosmic speed is about 11.2 km / s. Source of reference;-second cosmic speed What is the escape velocity of the solar system? The escape velocity of the solar system refers to the minimum initial velocity required for an object to completely get rid of the shackles of gravity. The escape velocity depends on the mass of the planet. If a planet has a large mass, its gravity is strong and its escape velocity is high. On the other hand, a lighter planet will have a smaller escape velocity. The escape velocity also depends on the distance between the object and the center of the planet. The closer the distance is, the greater the escape velocity is. The escape velocity of the earth is 11.2 km / s and that of the sun is 16.7 km / s. If the mass and surface gravity of a celestial body is so strong that the escape velocity reaches or even exceeds the speed of light, the celestial body is a black hole. The escape velocity of a black hole is 300000 km / s. The rate of an object when its kinetic energy is equal to its gravitational potential energy. The escape velocity is generally described as the minimum rate required to fly away from the gravitational field of gravity. The term "escape velocity" can be considered inappropriate because it is actually speed, not speed, that is, it indicates how fast the object must move, but has nothing to do with the direction of motion, except that it is not moving towards the gravity field. In more terms, the escape velocity is a scalar, not a vector. A physics problem of gravitation about black holes Solution: the distance between the star and the black hole is r = 6 billion km = 6X10 ^ 12m, and the star velocity VZ 2000km / s = 2X10 ^ 6m / S Let the mass of the black hole be M and the radius of the black hole is R (1). The gravity of the black hole provides the centripetal acceleration GM/r²=v²/r solution to obtain GM=v²r (1) (2) the escape velocity of the object on the surface of the black hole by analogy. Because high school does not learn the derivation of the second cosmic velocity, we can only use analogy. The first cosmic velocity on the earth is 7.8km/s, and the escape velocity is 11.2km/s. The escape velocity is twice the √ of the first cosmic velocity. If the first cosmic velocity on the black hole is √ (GM/R), then the escape velocity on the black hole is √ (2GM/R). (3) if an object moving at the speed of light just cannot escape, then √ (2GM/R) = c, that is, 2GM 2GM/R, that is, 2GMUniverse.
What is the escape speed of a black hole?