Ahousehold refrigerator that has a power input of 450 w and a cop of 1.5 is to cool five large watermelons, 10 kg each, to 8°c. if the watermelons are initially at 28°c, determine how long it will take for the refrigerator to cool them? the watermelons can be treated as water whose specific heat is 4.2 kj/kg·°c. is your answer realistic or optimistic?

Afull journal bearing has a journal diameter of 27 mm, with a unilateral tolerance of -0.028 mm. the bushing bore has a diameter of 27.028 mm and a unilateral tolerance of 0.04 mm. the l/d ratio is 0.5. the load is 1.3 kn and the journal runs at 1200 rev/min. if the average viscosity is 50 mpa-s, find the minimum film thickness, the power loss, and the side flow for the minimum clearance assembly.