4.94 liquid water enters a valve at 300 kpa and exits at 275 kpa. as water flows through the valve, the change in its temperature, stray heat transfer with the surroundings, and potential energy effects are negligible. operation is at steady state. modeling the water as incompressible with constant r ⫽ 1000 kg/m3, determine the change in kinetic energy per unit mass of water flowing through the valve, in kj/kg.

Air is to be cooled in the evaporator section of a refrigerator by passing it over a bank of 0.8-cm-outer-diameter and 0.4-m-long tubes inside which the refrigerant is evaporating at -20°c. air approaches the tube bank in the normal direction at 0°c and 1 atm with a mean velocity of 4 m/s. the tubes are arranged in-line with longitudinal and transverse pitches of sl- st 1.5 cm. there are 30 rows in the flow direction with 15 tubes in each row. determine (a) the refrigeration capacity of this system and (b) pressure drop across the tube bank. evaluate the air properties at an assumed mean temperature of -5°c and 1 atm. is this a good assumption?

Ahelical coil spring has a mean diameter of 50 mm, a wire diameter of 5.5 mm and is wound with a pitch of 10 mm. the spring steel has an ultimate strength of 1250 mpa. find the force needed to compress the spring solid and the wire stress in this condition. state whether the spring will return to its initial length.

Asimply supported beam abc of length l has ab of length hl and second moment of area / and bc of length hl and second moment of area i2. determine the strain energy stored in the beam when it is subject to a vertical load f at its midpoint and the consequential central deflection.