A neutron star has a density equal to that of the nuclear matter(=`3xx10^17`). Assuming the staar to be spherical, find the radius of a neutron star whose mass is `4.0xx10^30`kg (twice the mass of the sun ).

Answer

A

Explanation

We know `f = M/V`
`rArr V = M/f = (4 xx 10^(30))/(2.4 xx 10^(17))`
`= 1/(0.6) xx 10^(13)`
`=1/6 xx 10^(14)`
`V = 4/3 piR^3`
`rArr 1/6 xx 10^(14) = 4/3 xx pi xx R^3`
`rArr R_3 = 1/6 xx 3/4 xx 1/pi xx 10^(14)`
rArr R_3 = 1/8 xx 100/(pi) xx 10^(12)`
` :. R = 1/2 xx 10^(4) xx 3.17`
`= 1.585 xx 10^(4) = 15 km`.