Aballoon filled with helium gas has an average density of rhob = 0.27 kg/m3. the density of the air is about rhoa = 1.23 kg/m3. the volume of the balloon is vb = 0.084 m3. the balloon is floating upward with acceleration a.

The of a machine determines its "usefulness." a. input force b. output force c. mechanical advantage

Air initially at 0.75 bar, 1000 k, and occupying a volume of 0.12 m^3 undergoes two processes. process 1-2: the air is compressed isothermally until the volume is halved. process 2-3: the air undergoes a constant pressure process until the volume is halved again. assume ideal gas behavior. a) determine the mass of the air, in kg. b) the work and the heat transfer for each of the two processes, in kj. (100 kj = 1 bar . m^3)

How are the crust and the inner core alike? a) they are both solid. b) they both have the same temperature. c) they are both under the same pressure. d) they are both very close to the center of the earth.