A 12hp motor is used to drive an air compressor. The compressor efficiency is 70%. Find the mass of air in kg needed per minute if air is available at 30C. The pressure compresses to 8 times its original pressure. Ans: 1.52

A 400 lbm object accelerates from 10.0 ft/s to 17.5 ft/s. How much work has been done?

A torque of 2 N-m is necessary to rotate a paddle wheel at a rate of 20 rad/s.The paddle wheel is located in a rigid vessel containing a gas. What is the net work injoule done on the gas during 10 minutes of operation?

1 - Consider 2 kg of water in a cylinder blocked by a piston at 20 C, 200 kPa. Water is heated and piston starts to rise. When the piston reaches the blocks, the volume of water has doubled. Heating continues until the pressure also doubles. Calculate the work done by water and the amount of heattransfer. Consider the case that the piston is restricted by the linear spring. Initially the spring is at rest. Water is heated until the piston reaches the blocks. Just before it hits the blocks the pressure is twice the initial pressure. Calculate the work done by water and the amount of heat transfer by the time the piston reaches the blocks. 7 D H₂0