Aclosed system of mass 2 kg undergoes an adiabatic process. the work done on the system is 30 kj. the velocity of the system changes from 3 m/s to 15 m/s. during the process, the elevation of the system increases 45 meters. the acceleration of gravity is g -9.8 m/s2. determine the change in internal energy of the system in kj.

Amass of 1.5 kg of air at 120 kpa and 24°c is contained in a gas-tight, frictionless piston-cylinder device. the air is now compressed to a final pressure of 720 kpa. during the process, heat is transferred from the air such that the temperature inside the cylinder remains constant. calculate the boundary work input during this process.

Acompressor receives the shaft work to decrease the pressure of the fluid. a)- true b)- false

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.