A majorette in a parade is performing some acrobatic twirlings of her baton. Ass
ID: 1513995 • Letter: A
Question
A majorette in a parade is performing some acrobatic twirlings of her baton. Assume that the baton is a uniform rod of mass 0.120 kg and length 80.0 cm .
a) Initially, the baton is spinning about a line through its center at angular velocity 3.00 rad/s .(Figure 1) What is its angular momentum? Express your answer in kilogram meters squared per second.
b) With a skillful move, the majorette changes the rotation of her baton so that now it is spinning about an axis passing through its end at the same angular velocity 3.00 rad/s as before. (Figure 2) What is the new angular momentum of the rod?
Express your answer in kilogram meters squared per second.
Explanation / Answer
a)
moment of inertia (I) = mr^2 / 12
angular momentum (L) = Iw
L = [mr^2 / 12]*w
L = [(0.12 x 0.80^2) / 12]*3
L = 0.0192 kg-m^2/sec
L = 1.92 x 10^-2 kg-m^2/sec
b)
Angular momentum L = Iw.
When a rod spins about one end,
I = mr^2/3,
L = [mr^2/3]*w
L = [(0.12*0.80^2)/3]*3
L = 0.0768 kg-m^2/s.
L = 7.68 x 10^-2 kg-m^2/sec
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