Lecture 3 Black Holes

56 cards   |   Total Attempts: 188
  

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If the sun would turn into a black hold right now, what would happen to the Earth?
- Orbit of Earth not change
- the sun would feel the pull towards the centre
Suction and the Black hole
Only happens when u are close to the black hole
Most important force on the scale of the Universe
Gravity
What fights against gravity?
MOTION
- whether initial explosion of the universe/ ordinary motion
Gravity vs. Motion
Depends on how packed the mass is together
- Gravity stronger more mass and closely packed
- Moon is about as densely packed as the Earth but LESS mass therefore less gravity
Min Speed (velocity) to escape Earth's gravity
11.3 km/s to escape Earth's gravity
- 6379 kms up
What if the earth had more mass would the escape velocity be higher?
- YES if had more mass and KEPT its size gravity stronger there fore escape velocity would be higher
How do astronauts float in space?
Astronauts gravity is about 8.8
- Earth's gravity is 9.8
- Astronauts in constant free fall, they do crash like on earth becuase they are always moving and circling the earth
What does Einstein's SR tell us about matter and energy?
SR= tells us that matter and engery can not go faster than the speed of light
SR = tells us speed has a limit , motion
What does SR tell us about matter/ engergy and gravity?
Gravity has no known limit, similar
- Heavy objects, gravity will always be able to over come even the fastest motion and all other phenomena
Black Hole: velocity, reltaion to speed of light, escaping ability of light
Escape velocity is HIGHER than the SPEED OF LIGHT,
- nothing can escape the black hole since nothing can go faster than BH
- depends on how densily packed toegher, light cant escape
Why called Black and Hole descibe the meaning of each
BLACK: b/c no light can escape hence the compact object itself is invisible
HOLE: is like a whole in observable universe. If u enter a black hole, you leave the region of the Universe that we can observe with a telescope- Never return
If the earth turned into a black hole how would it feel?
- you would not feel a big difference
- cold
- dark b/c no sun
- the orbit would not change b/c does not circle the sun cirlces the other centre of the universe
What would happen the closer you get to a black hole?
- it doesnt SUCK in matter
- Black hold just a much more compact form of the same amount of mass
- a weird orbiting happens spiral in about 10 km away
- in front of the BH is dust around them
What would happen if the Sun turned into a black hole?
- the force of gravity on Earth would be the same and the orbit would not change at all
- Gravity is determined by mass!