- #1
riseofphoenix
- 295
- 2
The angular speed of the turntable with a woman on it? Help!
Ok so I understand part a (why it's counterclockwise. τ = Fr = (mg)(2) = (70)(9.8)(2) = +1372)
Part b is where I'm stuck...
This is what I did...
PEinitial + [STRIKE]KEinitial rotational[/STRIKE] = [STRIKE]PEfinal[/STRIKE] + KEfinal rotational
PEinitial = KEfinal rotational
mgh = (1/2)Iω2
(70)(9.8)(2) = (1/2)(540)ω2
1372 = 270ω2
1372/270 = ω2
5.08 = ω2
2.25 rev/s = ω
Convert to rad/s
2.25/2π rad/s = 0.358 rad/s, but the answer is 0.389.
Help! :( Where did I go wrong?
Ok so I understand part a (why it's counterclockwise. τ = Fr = (mg)(2) = (70)(9.8)(2) = +1372)
Part b is where I'm stuck...
This is what I did...
PEinitial + [STRIKE]KEinitial rotational[/STRIKE] = [STRIKE]PEfinal[/STRIKE] + KEfinal rotational
PEinitial = KEfinal rotational
mgh = (1/2)Iω2
(70)(9.8)(2) = (1/2)(540)ω2
1372 = 270ω2
1372/270 = ω2
5.08 = ω2
2.25 rev/s = ω
Convert to rad/s
2.25/2π rad/s = 0.358 rad/s, but the answer is 0.389.
Help! :( Where did I go wrong?