Let's figure out the energy and momentum associated with thatmotion.

For the purposes of this problem, treat the Earth as a solid,uniform sphere with mass 5.97×10²⁴ kg and radius6.37×10⁶ m , and assume that the Earth's orbit aroundthe sun is circular with a radius of 1.5×10¹¹ m .

Part A

What is the angular kinetic energy of the Earth due to its orbitaround the sun?

Part B

What is the magnitude of the Earth's angular momentum due to itsorbit around the sun?

Part C

What is Earth's angular kinetic energy due to its rotationaround its axis?

Part D

What is the magnitude of the Earth's angular momentum due to itsrotation around its axis?

Part E

Remember that energy and momentum are always conserved (thoughenergy can change forms). In other words, if you start with acertain amount of energy and momentum, you must end with the sameamount of energy and momentum. By conservation of energy andmomentum, the values you've calculated in this problem must havecome from somewhere.

Which of the following best explains where the Earth's angularkinetic energy and momentum came from?

Remember that energy and momentum are always conserved (thoughenergy can change forms). In other words, if you start with acertain amount of energy and momentum, you must end with the sameamount of energy and momentum. By conservation of energy andmomentum, the values you've calculated in this problem must havecome from somewhere.

Which of the following best explains where the Earth's angularkinetic energy and momentum came from?

a) The solar system formed from a massive cloud of gas anddust, which was slowly rotating. As the cloud collapsed under itsown gravitational pull, the cloud started to spin faster, just asan ice skater pulling his arms in will spin faster. Because all ofthe material that accreted to form the planet was rotating, theplanet was rotating as well.

b) As the Earth formed, it experienced a series of collisionswith asteroids and comets. These asteroids and comets hit the ballof rock that was forming into the planet off-center. Over time, theoff-center collisions gradually caused the planet to rotatefaster.

c) As the Moon orbits around the Earth, it creates tides on theEarth. Over time the tides have caused the Earth to rotate fasterand faster.

d) Sheer force of will.