Explain in terms of specific heat capacity why a hot water bottle is good at heating a bed.

Water has a very high specific heat capacity, it is fair to assume bed-sheets and bedding items have a much lower specific heat capacity. If an object has a high temperature and is in surroundings at a lower temperature, the object will transfer heat until the body and surroundings are the same temperature. Because water has a very high specific heat capacity, as it drops by 1degree a large amount of energy is released. This energy is transferred into the bedding, with a low specific heat capacity so the same amount of energy causes the bedding temperature to raise by more than 1degree.