Neutron stars consist only of neutrons and have unbelievably high densities. A typical mass and radius for a neutron star might be 5.8 x 1028 kg and 1.5 x 103 m. (a) Find the density of such a star. (b) If a dime (V = 2.0 x 10-7 m3) were made from this material, how much would it weight (in pounds)?

(a) Divide 5.8*10^28 kg by the volume of the star. The volume is (4/3)*pi*r^3.

(b) Multiply the density you get in (a) my 2*10^-7 m^3. That will give you the mass in kg. For the weight (actually, the mass) in lb, assume 2.2 lb per kg.