(1)Q=cm(t2-t1)
=cpV(t2-t1)
=4.2×103J/(kg·℃)*(1×103kg/m3)*0.5m3*(40℃-20℃)
= 4.2×107J
(2)Q=nqm
m=Q/nq=4.2×107J/(0.2*3.0×107J/kg)=7kg
(1)Q=cm(t2-t1)
=cpV(t2-t1)
=4.2×103J/(kg·℃)*(1×103kg/m3)*0.5m3*(40℃-20℃)
= 4.2×107J
(2)Q=nqm
m=Q/nq=4.2×107J/(0.2*3.0×107J/kg)=7kg