Estimate the angular momentum of a figure skater of mass 60 kg who is spinning a

Question

Estimate the angular momentum of a figure skater of mass 60 kg who is spinning at 310 rpm (see figure below). Assume her arms and legs are pulled in very close to her rotation axis. (You will model the moment of inertia of the skater as that of a cylinder.) Estimate the radius of the cylinder you will use. Calculate the angular momentum of the figure skater. (Use your estimate.) kg middot m^2/s The flywheel of an automobile engine is a solid disk with a mass of 8.9 kg and a radius of 21 cm and is rotating at 3950 rpm. If the entire rotational kinetic energy of the flywheel were converted to gravitational potential energy, to what height would the flywheel be lifted? Assume the flywheel is a uniform disk.

Explanation / Answer

4)
Some informations are missing
what id Ii and If
Some values must eb given

5)
I = 0.5*m*r^2
= 0.5*8.9*(0.21)^2
= 0.196 Kgm^2

w = 3950 rpm
= 3950*2*pi /60 rad/s
= 413.64 rad/s

use:
Kinetic energy = potential energy
0.5*I*w^2 = m*g*h
0.5*0.196*(413.64)^2 = 8.9*9.81*h
h= 192 m
Answer: 192 m

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