Question

(5c). (3p) his weight on the Apollo 11 spacecraft, where the acceleration of gravity was 6.6 N/kg. 13 6. (8 points) The mass of air in our classroom is assumed to be known, 870 kg. Approximating the room by a cuboid of length 15m, width 10 m and height 5 m, please find the density, specific volume, and enerifie weicht of the air in the room.

Answer 1

From the basic definitions,

6)

Density

$D=\frac{M}{V}$

where, M is mass and V is the volume occupied by the mass.

so in the question,

$M=870~kg$

$V=Length\times width\times height=15\times 10\times 5=750 ~m^{3}$

then,

$D=\frac{870}{750}=1.16~kg/m^{3}$

Specific volume

specific volume is the inverse of the density so

$v=\frac{1}{D}=\frac{1}{1.16}=0.862~m^{3}/kg$

Specific weight

Specific weight is the weight per unit volume,

$w=\frac{Mg}{V}=Dg$

where g is the acceleration due to gravity

then,

$w=1.16\times 9.8=11.368~N$