Question
(a) Explain the angular momentum with an appropriate diagram, and show that the magnitude of the angular momentum can be expressed as a product of moment of inertia and angular speed. (b) Suppose that an Olympic ice skater sets herself m rotation with an initial angular speed of 7.5 rad/sec, with the masses of her hands and leg outstretched when her moment of inertia is 40.25 kg.m^2. As she rotates, she pulls her hands and leg inward so that the new moment of inertia becomes 28.5 kg.m^2. What is her new angular speed?
Explanation / Answer
b)
here ,
for initial angular speed , wi = 7.5 rad/s
Initial moment of inertia , I1 = 40.25 Kg.m^2
final momoent of inertia , I2 = 28.5 Kg.m^2
using conservation of angular momentum ,
I1 * wi = I2 * wf
40.25 * 7.5 = 28.5 * wf
wf = 10.6 rad/s
the new angular speed is 10.6 rad/s