Can drilling wood really make a fire? Someone once tried to drill wood with an electric drill, but there was no flame, only smoke. Put a balloon into thousands of meters of water.

The word "drill" means rotation and friction here. This does not mean cutting.

Everyone knows that friction generates heat.

When the temperature reaches a certain height, a flame will be generated. It is true that the ancients' "drilling for fire" came from life experience.

If you stick the stick in front of the hand drill and press it on another board to turn, you will successfully see the phenomenon of "drilling wood for fire".

The second balloon problem

How to put a balloon under thousands of meters of water? What material is the balloon made of? Balloons made of ordinary materials will be crushed by pressure to a certain depth and will never return to the water surface.

Special shape, special material, just look at the submarine.