Answer: (Answers may vary.)
Dark and dull objects absorb more energy. Lighter colored and shiny objects absorb less energy.
Because the shiny can reflects more energy then the black- colored can, the shiny can absorbs less energy. The water in the black colored can gets warmer because:
The cans emit energy. This heats the water. An object, which is shiny, reflects light. The black material almost absorbs light and heat. Heated bodies operate in reverse, which determines how they radiate energy. The higher the absorption by an object, the higher the radiation level it has. Since the shiny can absorbed less energy, it radiated less energy into the water. Thus, the water in the shiny can was less warm than the water in the black can.
Explanation: plato/edmentum