This is due to conservation of angular momentum. Angular momentum goes as the momentum (mass x velocity) times the radius from the center. Therefore, if you shrink the radius the velocity must go up for the angular momentum to stay the same.
The amount of energy in our universe is constant. This is because the universe is a closed system, i.e. it doesn't exchange energy with anything else. However, since the universe is expanding, the energy is getting spread out thinner and thinner, which will eventually lead to the heat death of the universe.
The Earth is much more massive than the moon, so its attractive force is much stronger according to Newton's Law of Gravity. Why, then, does the moon orbit the Earth instead of crashing into it?
Contrary to popular belief, the attractive force between the Earth and the Moon are exactly the same, i.e the Moon pulls on the Earth as much as the Earth pulls on the Moon. Since, for all intensive purposes, the only force on the Moon is the gravitational pull of the Earth and it is moving very fast (~1 km/sec), the Moon keeps "falling" out of the way of Earth's surface. It is the same principle as the cannonball demo Dr. Plavchan did in class.
Why does an object rotate faster as it shrinks its radius?
ReplyDeleteThis is due to conservation of angular momentum. Angular momentum goes as the momentum (mass x velocity) times the radius from the center. Therefore, if you shrink the radius the velocity must go up for the angular momentum to stay the same.
Deletedoes the amount of energy in our universe from the big bang dissipate slowly over time or does it just remain constant?
ReplyDeleteThe amount of energy in our universe is constant. This is because the universe is a closed system, i.e. it doesn't exchange energy with anything else. However, since the universe is expanding, the energy is getting spread out thinner and thinner, which will eventually lead to the heat death of the universe.
DeleteThe Earth is much more massive than the moon, so its attractive force is much stronger according to Newton's Law of Gravity. Why, then, does the moon orbit the Earth instead of crashing into it?
ReplyDeleteContrary to popular belief, the attractive force between the Earth and the Moon are exactly the same, i.e the Moon pulls on the Earth as much as the Earth pulls on the Moon. Since, for all intensive purposes, the only force on the Moon is the gravitational pull of the Earth and it is moving very fast (~1 km/sec), the Moon keeps "falling" out of the way of Earth's surface. It is the same principle as the cannonball demo Dr. Plavchan did in class.
DeleteThis comment has been removed by the author.
ReplyDelete