What is the hardest part of thermodynamics?

Abrake has a normal braking torque of 2.8 kip in and heat-dissipating cast-iron surfaces whose mass is 40 lbm. suppose a load is brought to rest in 8.0 s from an initial angular speed of 1600 rev/min using the normal braking torque; estimate the temperature rise of the heat dissipating surfaces.

The characteristic roots of a dynamic system are: 1.7920 1.8160 i, -1.7920 1.8160 i, -0.4160 what is the order of this system? what are the settling time and damping ratio of the system?

1kg of water contained in a piston-cylinder assembly undergoes two processes in series from an initial state where the pressure is 3.0 bar and the temperature is 150°c process 1-2: the water is compressed isothermally to a volume of 0.25 m^3 with 120 kj of work being done to the system. process 2-3: the water is heated at constant volume to a final pressure of 10 bar. a. find the change in internal energy for the system. b. calculate the amount of heat transferred, in kj. c. sketch both processes on a t-v diagram. (196.33 kj/kg, 76.33 kj)