Bare Hand Bottle Busting- Science Investigation

You two guys are definitely Phineas and Ferb

When they both had different theories I was like oh no it’s like the two smart kids in class getting different answers

This never gets old watching it again.

Me after watching this video: “excuse me, friend, can I interest you in this delicious bottle of hot water?”

Literally every time: Mark Rober: High-Speed Projectiles! Backyard Scientist: Set Everything on Fire!

Rubber mallet is a good idea. I can't tell you how many times I hurt my hand trying this.

From a fluid dynamics perspective: It seems to me that hitting the top of the bottle sends a shockwave through the water. Shockwaves have extremely low pressure at the front of the shock and extremely high pressure at the back of the shock. When the front of the wave reaches the bottom of the bottle, that low pressure zone generated by the shockwave induces cavitation (the little pocket of vapor you see at the bottom of the bottle). The water cant hold onto the air bubbles that are already dissolved in it or stay in its liquid phase in this low pressure zone, similar to why boiling water is much easier at the top of a mountain; the atmospheric pressure is less. When the energy of the shockwave dissipates, this vapor bubble (cavitation) collapses...very, very, violently. Often times at supersonic speeds. The force of that vapor bubble collapsing at supersonic speeds (which brings the water crashing down onto the bottom of the bottle), is what breaks the bottle, in my opinion. Perhaps Schlieren imaging could confirm this. It would follow that the CO2 bubbles in carbonation interrupt this shock wave from passing through the liquid, and keep the wave from reaching the bottom with enough energy to induce cavitation. The low pressure zone generated by the shockwave would cause the CO2 bubbles to escape from the liquid, causing the foaming in the beer you see This phenomenon is very similar to the cavitation seen in boat propellers. The propeller spins through the water, generating a low pressure zone behind the blades of the propeller, and when this pressure is low enough, the water can no longer stay in it's liquid phase, releasing any dissolved gas and changing phase to water vapor, generating the vapor bubble you see behind the propeller. When the energy from the propeller dissipates, these vapor bubbles collapse at supersonic speeds, changing the phase back to liquid and dissolving any air/gases back into the water, but at the same time gouging a chunk of metal out of the propeller. Edit: I've edited this post to clarify a few things, thanks to those who commented below!

"So as firm believers of science..." when you hear that

Tried it at home. Broke all the beer bottles in my fridge. Now dad is beating me. Thank you. very much...

Imagine pulling out some kerosene snowballs during a snowball fight

I learned to do this forty plus years ago, while in college. I always did this the hard way, with coke bottles having thicker glass. Plus seeing why this works would have led to better results.

4:03 the moment when you are absolutely, and the absolute joy, these slomo cams brought a new dimension to science

I totally think that Mark Rober, Backyard Scientist and the Slow-Mo guys need to make some of these videos together

Me: It's definitely just air pressure mark: It's not air pressure Me: It's not air pressure

Yes! Glad you did this! I, too, thought it was the air pressure forcing the liquid down. I was taught in my teens (in the 80's) by a friend to use wine bottles! No wonder they worked so well being non-carbonated. Thankfully, only about 3 out of 50 have broken in my hand while attempting this.

I love your videos! You do such a good job on them!

5:22 Who the hell screams ”gonnorhea” when they hurt themselves

The Slow-Mo Guys wants to know your location

I skipped the first part so all I heard was “you should set those on fire” But I only saw the kids so i was like “Set ThE kiDS oN FiRE?”

Alright ima invite my friends over and give them a beer bottle with hot water it nail polish remover and hit the bottle. What kind of day is that