Aspacecraft is traveling in space far from any planets or stars. how much force is required to maintain the spacecrafts speed? 1/2 the mass of the spacecraft 1/4 the mass of the spacecraft none twice the mass of the spacecraft i feel like its none, since there are no planets or stars to exert force on the rocket but id like to be sure.

The air in an automobile tire with a volume of 2.60 ft3 is at 70°f and 21 psig. determine the amount of air that must be added to raise the pressure to the recommended value of 30 psig. assume the atmospheric pressure to be 14.6 psia and the temperature and the volume to remain constant. the gas constant of air is ru = 53.34ft⋅lbflbm⋅r(1 psia144 lbf/ft2) = 0.3704 psia⋅ft3lbm⋅r the amount of air that must be added to raise the pressure is lbm