First, let's make some convertions:
[tex]268kg*\frac{1 lbm}{0.454kg}= 590.84 lbm[/tex]
[tex]133.7 ft^3*\frac{1m^3}{35.3147ft^3} = 3.78m^3[/tex]
a) weight of the fuel:
Newtons: The weight in newtons is equal to the mass in kilograms times the gravity in m/s^2.
[tex]W = m*g = 268kg*9.81m/s^2=2629.08 N[/tex]
lbf: The weight inlbf is equal to the mass in slugs times the gravity in ft/s^2.
[tex]W= m*g = 590.84 lbm *\frac{1 slug}{32.174lbm} *32.174ft/s^2 = 590.84 lbf[/tex]
b) density:
The density is the mass in kg of the fuel divided by its volume in m^3:
[tex]d = \frac{m}{v} =\frac{268kg}{3.78m^3} =70.9 kg/m^3[/tex]
c) specific volume:
The specific volume is the volume in ft^3 of the fuel divided by its mass in lbm:
[tex]v_{sp} = \frac{v}{m} =\frac{133.7 ft^3}{590.84 lbm} = 0.226 ft^3/lbm[/tex]
