Which would you say is a more necessary form of energy?

Question

Thermal energy, or the chemical energy from food?

My friend and I got in an argument about this in class. He said thermal, and I sort of agree with him. But the teacher said it was food energy. So I just went with what the teacher said. But my friend kept insisting that it was thermal energy. So what would you say is more important?

Answer 1

If you eat food, you gain energy from it which is necessary to survive.  If you were only supplied thermal energy, for example from a radiator, you would be warm, but then you would die from lack of food energy.  However, eating also helps you (and any warm-blooded creature) to create their own heat.  So, in that way, food energy is more important.

Answer 2

All energy on this Earth (with the exception of under sea vents) comes from the sun, which is mostly thermal energy.

This includes the chemical energy from food. Food is more important to us animcals.. but it all comes from thermal.

Another way of looking at it is that you can freeze to death in a matter of minutes/hours (depending on the temperature ie. lack of thermal energy) while you can survive without food for about 3 weeks.