This is a conservation of angular momentum question.
Li = I1 omegai + I2 omegai
I1 given
I2 = mr^2 times 2 (since 2 books)
omegai is the same for both (convert to rad/sec)
Lf = I1 omegaf + I2 omegaf
compute new I2
Li=Lf and solve for omegaf
b) KEi = 1/2I1 omegai^2 + 1/2I2 omegai^2
do same for KEf
A student on a piano stool rotates freely with an angular speed of 3.07 rev/s. The student holds a 1.38 kg mass in each outstretched arm, 0.759 m from the axis of rotation. The combined moment of inertia of the student and the stool, ignoring the two masses, is 4.72 kg·m2, a value that remains constant.
a. As the student pulls his arms inward, his angular speed increases to 3.54 rev/s. How far are the masses from the axis of rotation at this time, considering the masses to be points?
b. Calculate the initial and final kinetic energy of the system.
1 answer