A gymnast of rotational inertia 65 kgm2 is tumbling head over heels with angular

Question

A gymnast of rotational inertia 65 kgm2 is tumbling head over heels with angular momentum 460 kgm2/s .

Part A

What is her angular speed?

Exercise 11.27

A potter's wheel, with rotational inertia 6.60 kgm2 , is spinning freely at 19.0 rpm . The potter drops a 2.80 kg lump of clay onto the wheel, where it sticks a distance of 46.0 cm from the rotation axis.

Part A

What is the subsequent angular speed of the wheel?

Exercise 11.28

A 2.6-m-diameter merry-go-round with rotational inertia 120 kgm2 is spinning freely at 0.60 rev/s . Four 25-kg children sit suddenly on the edge of the merry-go-round.

Part A

Find the new angular speed.

Part B

Determine the total energy lost to friction between the children and the merry-go-round.

Exercise 11.30

A skater has rotational inertia 4.2 kgm2 with his fists held to his chest and 5.7 kgm2 with his arms outstretched. The skater is spinning at 3.0 rev/s while holding a 2.5-kg weight in each outstretched hand; the weights are 76 cm from his rotation axis.

Part A

If he pulls his hands in to his chest, so they’re essentially on his rotation axis, how fast will he be spinning?

Explanation / Answer

A) Angular momentum = I w

460 kg m^2 s = (65 kg m^2) w

w = 7.08 rad/s

B) angular mommentum for wheel and caly will be constant.

Iiwi = If wf

(6.60)(19) + 0   = ((6.60) + (2.80 x 0.46^2))(w)

125.4 = 7.19w

w = 17.4 rpm

Related Questions

Navigate

• Browse (All)
• Browse A
• Subjects

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.