Certain neutron stars (extremely dense stars) are believed to be rotating at about 10 rev/s. if such a star has a radius of 18 km, what must be its minimum mass so that material on its surface remains in place during the rapid rotation in kilograms?

mass of the neutron star =3.45185×10^26 Kg

Explanation:

When the neutron star rotates rapidly, a material on its surface to remain in place, the magnitude of the gravitational acceleration on the central material must be equal to magnitude of the centripetal acc. of the rotating star.

That is

M_ns = mass odf the netron star.

G= gravitational constant = 6.67×10^{-11}

R= radius of the star = 18×10^3 m

ω = 10 rev/sec = 20π rads/sec

therefore,

= 3.45185... E26 Kg

= 3.45185×10^26 Kg