a) Ta có: \(Q=Q_{Cu}+Q_{nước}=0,3\cdot380\cdot\left(100-15\right)+1\cdot4200\cdot\left(100-15\right)=366690\left(J\right)\)
b) Ta có: \(Q_{thu}=Q_{tỏa}\)
\(\Rightarrow3\cdot4200\cdot\left(t-30\right)=1\cdot4200\cdot\left(100-t\right)\)
\(\Rightarrow t\approx47,5^oC\)