Why gravity gets so strong near dense objects | Cosmology & Astronomy | Khan Academy
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Why Gravity Gets So Strong Near Dense Objects. Created by Sal Khan. Watch the next lesson: https://www.khanacademy.org/science/physics/cosmology-and-astronomy/earth-history-topic/plate-techtonics/v/plate-tectonics-difference-between-crust-and-lithosphere?utm_source=YT&utm_medium=Desc&utm_campaign=cosmologystronomy Missed the previous lesson? https://www.khanacademy.org/science/cosmology-and-astronomy/stellar-life-topic/cepheid-variables/v/why-cepheids-pulsatehttps://www.khanacademy.org/science/cosmology-and-astronomy/earth-history-topic/plate-techtonics/v/plate-tectonics-difference-between-crust-and-lithosphere?utm_source=YT&utm_medium=Desc&utm_campaign=cosmologystronomy Cosmology & Astronomy on Khan Academy: The Earth is huge, but it is tiny compared to the Sun (which is super huge). But the Sun is tiny compared to the solar system which is tiny compared to the distance to the next star. Oh, did we mention that there are over 100 billion stars in our galaxy (which is about 100,000 light years in diameter) which is one of hundreds of billions of galaxies in just the observable universe (which might be infinite for all we know). Don't feel small. We find it liberating. Your everyday human stresses are nothing compared to this enormity that we are a part of. Enjoy the fact that we get to be part of this vastness! About Khan Academy: Khan Academy offers practice exercises, instructional videos, and a personalized learning dashboard that empower learners to study at their own pace in and outside of the classroom. We tackle math, science, computer programming, history, art history, economics, and more. Our math missions guide learners from kindergarten to calculus using state-of-the-art, adaptive technology that identifies strengths and learning gaps. We've also partnered with institutions like NASA, The Museum of Modern Art, The California Academy of Sciences, and MIT to offer specialized content. For free. For everyone. Forever. #YouCanLearnAnything Subscribe to Khan Academy’s Cosmology & Astronomy channel: https://www.youtube.com/channel/UChNPnEkW8LYZ5Rwi8_A2-DA?sub_confirmation=1 Subscribe to Khan Academy: https://www.youtube.com/subscription_center?add_user=khanacademy
Comments
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What will happen IF two black holes collide.
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thank you so much , you made it so clear
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Well, in the second case he approached de m2 to the center of m1. yeah, because m1 got compressed, but what would be the F2, if the m1 stayed in place? Would it be the same? I think yes because r1=r2 so f1=f2? right?
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Can someone please help me! I don't understand why when you are in the center of the object, everything surrounding would be exerting a force away from you. Wouldn't it still be pulling in towards the center and therefore you?
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On the contrary, the black hole taking on more mass increases the mass density and therefore increases the gravitational effect of the black hole. That being said, due to certain loop holes with Quantum Mechanics near the even horizon, black holes can "evapourate" a certain amount of energy/mass in the form of Hawking radiation and, hence a black hole can lose mass and evapourate into nothing.
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I wonder: Could a black hole ever become a non-black hole again? Because i swallows a lot of extra mass towards it, but the density of the extra mass is smaller, so the total gravity of the object should get lower and lower until a point light can escape again and it's no longer a black hole, right?
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I wish I had a physics teacher like you when I was at school! Outstanding. Thanks.
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This is awesome, I finally understand Schwarzschild Radius.
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the don't have infinite mass...they have infinite density.
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Thank's.
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Black holes do not have infinite mass but they are believed to have infinite mass density which defines them as a singularity, a finite amount of mass contained within an infinitely small space which gives their infinite mass density. (density = mass/volume => m/lim->0 = infinite).
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If a black hole has infinite mass why doesn't it have infinite gravity?
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I don't really think the statement, but it kind of implies that dense objects have more gravity.
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@uru39 My understanding is that the evolution of stars is dependent on their mass, a Sol-sized star will become a White dwarf as the electrical forces balance gravitational collapse against energy release. Larger stars (2 x Sol) need nuclear forces to balance this and become neutron stars. Still more massive stars (3 x Sol) cannot balance gravitational collapse and become black holes.
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No problem!
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In hindsight it's so obvious! Thanks!
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It's just the fact that if you do the maths, the attractive force due to gravity is not strong enough the account for the very large repulsive force due to electromagnetism. The charge of a proton is relatively massive compared with the mass of a proton.
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Stupid question. I know it is the strong force that holds protons together, but why would gravity be so comparatively weak? Both the mass and the radius are very very small, but how are protons not considered dense enough to hold each other together by gravity? Does it have something to do with the empty space in an atom (maybe it's weight or it's properties?) or is it something else that makes this force fairly negligible?
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Are you self taught on all of this through research or are you in university? you know alot about history and politics aswell so im just curious
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Photons move in a straight line through space. If space its self is curved by a large object, the light will move through those contours. From the lights perspective it is moving straight, it is space that is curved.
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