The aluminum rod AB (G 5 27 GPa) is bonded to the brass rod BD (G 5 39 GPa). Knowing that portion CD of the brass rod is hollow and has an inner diameter of 40 mm, determine the angle of twist at A.

Amixture of gases consists of 0.4 kg of oxygen, 0.7 kg of carbon dioxide, and 0.2 kg of helium this mixture is maintained at 100 kpa and 27°c. determine: (a) the apparent molecular weight of this mixture the volume it occupies (b) the partial volume of the oxygen, and (c) (d) the partial pressure of the helium