Question

Calculate the mass (in kg) of the following objects:

(a) Copper rod of length 32.0 cm and diameter 4.6 cm

(b) Aluminum sphere of diameter 5.80 cm

(c) Gold disk of diameter 8.0 cm and thickness 12.4 mm.

(d) Hollow cylindrical pipe of brass with length 2.50 m, inner diameter 42.0 mm and outer diameter 54.0 mm.   

Answer 1

a)
given
L = 32 cm = 0.32 m
d = 4.6 cm = 0.046 m
we know, density of copper rho_copper = 8960 kg/m^3

mass = density*volume

= rho_copper*pi*r^2*L

= 8960*pi*(0.046/2)^2*0.32

= 4.77 kg <<<<<<<<<-------------Answer

b) d = 5.8 cm = 0.058 m
we know, density of aluminum rho_aluminum = 2700 kg/m^3

mass = density*volume

= rho_aluminum*(4/3)*pi*r^3

= 2700*(4/3)*pi*(0.058/2)^3

= 0.276 kg <<<<<<<<<-------------Answer

c)

given
L = 12.4 mm = 0.0124 m
d = 8.0 cm = 0.08 m
we know, density of gold rho_gold = 19320 kg/m^3

mass = density*volume

= rho_gold*pi*r^2*L

= 19320*pi*(0.08/2)^2*0.0124

= 1.20 kg <<<<<<<<<-------------Answer

d)

mass = density*volume

= rho_brass*pi*(r2^2 - r1^2)*L

= 8730*pi*( (0.054/2)^2 - (0.042/2)^2 )*2.5

= 19.7 kg <<<<<<<<<-------------Answer