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

Rotational Kinetic Energy

  • Thread starter unteng10
  • Start date
  • #1
10
0

Homework Statement


A skater spins with an angular speed of 17.4 rad/s with his arms outstretched. He lowers his arms, decreasing his moment of inertia from 43 kg/m^2 to 37 kg/m^2. Calculate his initial and final rotational kinetic energy.



Homework Equations


L=I[tex]\omega[/tex]
KE=1/2I[tex]\omega[/tex]^2



The Attempt at a Solution


Not sure if im on the right track here, for initial kinetic energy I came up with 3.53 J. I manipulated L=I[tex]\omega[/tex] to get [tex]\omega[/tex]=L/I to find my angular velocity. Then plugged that in the KE=(1/2)(43 kg/m^2)(.405^2) to get 3.53 J. Did I do this correctly?
 

Answers and Replies

  • #2
rl.bhat
Homework Helper
4,433
5
A skater spins with an angular speed of 17.4 rad/s
This is not the angular momentum L, but is is the angular velocity w.
 
  • #3
10
0
Okay, so the speed would be [tex]\omega[/tex]?
 
  • #4
rl.bhat
Homework Helper
4,433
5
Okay, so the speed would be [tex]\omega[/tex]?
Yes. Angular speed is w.
 

Related Threads for: Rotational Kinetic Energy

Replies
2
Views
2K
  • Last Post
Replies
5
Views
2K
  • Last Post
Replies
0
Views
2K
  • Last Post
Replies
2
Views
500
  • Last Post
Replies
1
Views
2K
  • Last Post
Replies
7
Views
595
  • Last Post
Replies
5
Views
2K
  • Last Post
Replies
10
Views
2K
Top