((QUESTION 1)) A 19-kg rotating disk of radius 0.20m has an angular momentum of
ID: 1309024 • Letter: #
Question
((QUESTION 1))
A 19-kg rotating disk of radius 0.20m has an angular momentum of 0.35kg?m2/s .
Part A
What is the angular speed of the disk?
Express your answer using two significant figures.
((QUESTION 2))
An ice skater has a moment of inertia of 3.0kg?m2 when his arms are outstretched and a moment of inertia of 1.0kg?m2when his arms are tucked in close to his chest.
Part A
If he starts to spin at an angular speed of 1.4rps (revolutions per second) with his arms outstretched, what will his angular speed be when they are tucked in?
Express your answer using two significant figures.
? =______________ rad/sExplanation / Answer
1)
0.5*M*R^2 = I
I = 0.38
L =I*w
Therefore w = 0.35/0.38
w = 0.921
2)
Conservation of angular momentum
L1w1 = L2w2
3*1.4 = 1*w2
w2 = 4.2 rps
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