I need Help. Rotational Kinetic Energy of Earth and the Moon.

  • #1

Homework Statement



What is the ratio of the rotational kinetic energy of the Earth to the rotational kinetic energy of the Moon as they spin about their axes?

The Attempt at a Solution




Me = Mass of Earth (5.97 × 1024 kg)
Re = Radius of Earth (6.37 × 106 m)
Mm = Mass of Moon (7.35 × 1022 kg)
Rm= Radius of Moon (1.74 × 106 m)

this is all i know I don't know where to start. I know KE=(1/2)(moment of inertia)(angular velocity)
 

Answers and Replies

  • #2
45
0
The moment of inertia for a sphere is
[tex]I = \frac{2}{5}MR^2[/tex]

And you can find the angular velocity for the Earth because you know it has a period of one day. I think you'll have to find the length of a day on the moon.

After that just divide the two energies, you've got the right equation and all the rest of the right info though.
 

Related Threads on I need Help. Rotational Kinetic Energy of Earth and the Moon.

Replies
1
Views
26K
Replies
1
Views
559
Replies
2
Views
14K
Replies
8
Views
28K
Replies
1
Views
958
Replies
15
Views
875
Replies
2
Views
2K
Replies
5
Views
9K
Replies
6
Views
8K
  • Last Post
Replies
5
Views
9K
Top