posted by Kathryn .
How much energy is needed to heat and melt 3.0 kg of copper initially at 83°C?
Be mindful of significant figure rules for both multiplication and addition
melting point of copper = 1083.0 °C
heat capacity of copper = .39 kJ/kg-K
heat of fusion of copper = 207 kJ/kg
so to warm it up
Qin = .39 kJ/kgK(1083-83)K(3kg) = 1170 kJ
then to melt it
Qin = 207kJ/kg (3 kg) = 621 kJ
total Qin = 1791 kJ or 179,100 J