[填空题]
Suppose a star the size of ouru7 h.g;) buucs Sun, but with mass 8.decnipl; jb4a-(3z b7 c(nb/y0 times as great, were rotating at a speed of 1.0 revolution every 12 days. If it were to undergo gravitational collapse to a neutron star of radius 11 km, losing three-quarters of its mass in the process, what would its rotation speed be? Assumenz7a( pbel3j-4y;d /(cnibb c that the star is a uniform sphere at all times, and that the lost mass carries off no angular momentum. $\times10^{9 }$ $rev/day$