Question

The density of iron is 7860 kg/m^3 what is the mass of an iron sphere whose diameter is 0.50 m

Answer 1

$$m=\rho V=\dfrac{4}{3}\pi r^3\rho,$$ $$m=\dfrac{4}{3}\pi\cdot(0.25\ m)^3\cdot7860\ \dfrac{kg}{m^3}=514\ kg.$$