A 500 W iron has a base plate of thickness Lp = 0.5cm, made of aluminum alloy ( = 3000 kg/m 3;cp = 900 J/(kgK)) with a high thermal conductivity(k = 180 W/(mK)). One side of the base plate is incontact with resistance wires that generate heat; theother side of the base plate is exposed to air and hasa surface area A p = 0.03 m 2. The convective heattransfer coefficient between the base plate and theair is h = 12 W/(m 2K). Initially, the iron has the sametemperature as the surrounding air, Tair = 20C.