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Unformatted text preview: H2.2 A rnass of 15 kg of air in a piston-cvlindcr dcvice is heated fronr 25 tct 77"C by passing current through a resistarlce heater inside the cylindcr. The pressure irr the cylinder is hcld corlstant at 300 kPa during the process. and a licat ioss of 60 kJ occurs. Deterrnine the electric energ)' suppliecl. in K\Vh. Assurne idcal gas behavior arrd a. variable specific lieats b. corrstarit spccific hcats Corrrparc solrrtions from a. unci b. a,rrd corrrrrterrt. FI2.3 A gzrllon of rnilk at 68'F is place in a relrigerirtor. It thc ratc of hea,t trarrsfer fioui thc niilk is constarit at 0.08 Btu/s. hou, krng lvill it take (rriinutcs) fbr thc rnilk to cool to,10'F''l Assunre rrrilk behaves as arr irrcorripressiblc substancc u,ith specific heat aricl clcrrsitv vilhres oi 0.9"1 Iltu/lbn'R and 64 lbrn/ft3. respcctivclv. i" ld Y Figrrre II2.1...
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- Spring '08