Question

Would it be more efficient to warm your bed on a cold night with a hot water bottle that contains 1 kg of water at 50 degrees C or with a 1 kg gold bar at 50 degrees C?

Answer 1

It would be more efficient with the hot water bottle. The specific heat of water is a whopping 4.2 kJ/kg*°C while that of gold is only 0.13 kJ/kg*°C.

But I still have my bed warmer from Holland hanging on my wall! It's a lovely copper "pot" that held hot coals with a long wooden handle!

Sra (aka Mme)