Answer:
Mass of the disc in pounds is 45.288 lbm
Explanation:
Thickness of the disc [tex]t=3 inch=3\times 2.54=7.62 mm=7.62\times 10^{-3} m[/tex]
diameter of the disc [tex]d=0.4 m[/tex]
Density of the platinum [tex]\rho =21450 kg/m^3[/tex]
Volume of the disc
[tex]V=\frac{\pi d^2}{4} \times t\\V=\frac{\pi \times 0.4^2}{4} \times 7.62\times 10^{-3}\\V=9.57\times 10^{-4} m^3[/tex]
Mass of the disc
[tex]M=\rho \times V\\M=21450\times 9.5755 \times 10^{-4}\\M=20.539 kg[/tex]
Mass of the disc in pounds is
[tex]M\times 2.205 =20.539\times 2.205=45.288 lbm[/tex]
