A person with a body temperature of 37°C holds an ice cube with a temperature of 0°C in a room where the air temperature is 20.°
C. The direction of heat flow is (1) from the person to the ice, only
(2) from the person to the ice and air, and from the air to the ice
(3) from the ice to the person, only
(4) from the ice to the person and air, and from the air to the person
The answer is (2). Heat always flows down the temperature gradient, from high temperature to low temperature. Therefore, since the person is the warmest, heat flows from the person to both the ice and the air. Additionally, since the air is warmer than the ice, heat flows from the air to the ice.
