Pdas with two stacks are strictly more powerful than pdas with one stack. prove that 2-stack pdas are not a valid model for cfls by giving an example of a language that is not context-free and yet accepted by a 2-stack pda. describe (no math necessary) how a 2-stack pda would accept that language.

An open feedwater heater operates at steady state with liquid entering at inlet 1 with t? = 40°c and pl = 1 .2 mpa. water vapor att2-200°c and p2 = 1.2 mpa enters at inlet 2. saturated liquid water exits with a pressure of pa 1.2 mpa. neglect heat transfer with the surroundings and all kinetic and potential energy effects, determine the mass flow rate of steam at inlet 2 if the mass flow rate of liquid water at inlet 1 is given as 2 kg/s.