Equal amounts of a liquid metal at the same temperature are poured into three moulds made of steel, copper and aluminum. The shape of the cavity is a cylinder with 15 mm diameter. The size of the moulds are such that the outside temperature of the moulds do not increase appreciably beyond the atmospheric temperature during solidification. The sequence of solidification in the mould from the fastest to slowest is
(Thermal conductivities of steel, copper and aluminum are $60.5$, $401$ and $237$ $W$/$m-K$, respectively. Specific heats of steel, copper and aluminum are $434, 385$ and $903$ $J$/$kg-K$, respectively. Densities of steel, copper and aluminum are $7854$, $8933$ and $2700$ $kg/m^3$, respectively.)
- Copper - Steel - Aluminum
- Aluminum - Steel - Copper
- Copper - Aluminum - Steel
- Steel - Copper - Aluminum