If you could grind up say 60 calories (1/3cup) of Kellogg's cereal and arrange to convert all the energy into explosive force under an aluminum pop can with a mass of 20gr, how high would the can fly..

a.- (I can believe I never tried this with one of my kids)

Remember that the 60 calories are determined to be 60 calories usable by the body. If there is anything that can't be digested, it will also have additional caloric value as an explosive - so the energy released will likely be over 60 calories.

Also, if you mix it with an oxidizer and detonate it quickly, it will likely simply rip the pop can apart and dissipate energy in all directions. The can may not go very high.

IF you could convert 60 Cal of chemical energy in the food into kinetic energy at 100% efficiency (which is obviously impossible) and if you ignore air resistance, the can would fly to a height of 1281 meters! Here is the calculation:

60 Calories of food energy = 60 Kcal (the "Calories" - capital "C" - in a serving of food as printed on the side of the cereal carton is actually Kilo-calories).

60 Kcal * 4.184 Joules/Kcal = 251 Joules of energy available from the cereal.

Converting all this energy to an increase in the can's potential energy under earth gravity, using PE = mgh, you have:

251 Joules = 0.02 kg * 9.8 m/s^2 * h

Solve for h, and you get 1281 meters.

Again, this is all theoretical. I have no idea how you would actually make this happen using Corn Flakes as your energy source.