A star rotates about its axis through a diameter once in 50 days. At the end of its life, the star collapses to one-hundreth of its original diameter. The rate of rotation of the collapsed star will be:
a. 0.02 rotaions per day
b. 20 rotaions per day
c. 2 rotaions per day
d. 200 roations per day
Answer: d. 200 rotations per day
From conservation of angular momentum
I1w 1 = I2w ...
The solution calculates the rate of rotation of the collapsed star.