The following are the impulse responses of continuous-time LTI systems. Determine whether each system is causal and/or stable. Justify your answers. (a) h(t) = e-4r u(t- 2) (b) h(t) = e-6t u(3 - t) (c) h(t) = e-2r u(t + 50) (d) h(t) = e21 u( -1 - t)

Air inially occupying a volume of 1 m2 at 100 kpa, 27 c undergoes three internally reversible processes in series. process 1-2 compression to 500 kpa during which pv constant process 2-3 adiabatic expanslon to 100 kpa process 3-1: constant-pressure expansion to 100 kpa (a) calculate the change of entropy for each of the three processes. (b) calculate the heat and work involved in each process. (c) is this cycle a power cycle or refrigeration cycle?