• Support PF! Buy your school textbooks, materials and every day products Here!

Rotational kinetic energy and moment of inertia

  • Thread starter court2011
  • Start date
  • #1
14
0

Homework Statement



A 16 g CD with a radius of 6.0 cm rotates with an angular speed of 42 rad/s.
(a) What is its kinetic energy?

Homework Equations



k=1/2Iw^2

The Attempt at a Solution


k=1/2(0.016x0.0036)(1764)=0.05 J
 

Answers and Replies

  • #2
ideasrule
Homework Helper
2,266
0
Careful. The moment of inertia of a disk is not MR^2. That's the moment of inertia for a hoop, or for a point mass.
 
  • #3
14
0
ohhh so should i have 1/2mr^2
 
  • #4
ideasrule
Homework Helper
2,266
0
Yup.
 
  • #5
14
0
kk sweet thanks! i got it right :)
 

Related Threads for: Rotational kinetic energy and moment of inertia

Replies
3
Views
4K
Replies
6
Views
9K
Replies
2
Views
4K
Replies
2
Views
1K
Replies
6
Views
5K
Replies
1
Views
2K
  • Last Post
Replies
2
Views
4K
Replies
2
Views
3K
Top