DrPizza
Administrator Elite Member Goat Whisperer
Okay...
So, in physics class, I'm doing my end of the year labs. Kids have already met the lab requirements, so the labs are completely fun, and mostly for review.
We're doing a lab where they design and test, make modifications (one of the standards is in engineering for science), etc.
They're building rockets, and using a 2 liter bottle for the engine - 1/2 full of water, and at 100psi. Heck of a lot of thrust from those things (video analysis calculated the acceleration at about 100 times the acceleration from gravity)
The conclusion of the lab is a contest - students have to launch a raw egg into the air using their rocket. Whoever's egg stays up the longest, and returns without breaking is the winner.
To make it fair, I added a pressure regulator so no one could exceed 100psi. I was adjusting it during lab time today (and I was also watching a small studyhall). Pumped a bottle up to 100psi with air only. Physics kids could hardly contain the laughter as they knew what a loud bang it was going to make as I launched the empty bottle under a desk. They knew the studyhall kids would jump out of their seats. (and, they did)
Well, now, imagine propelling an empty 2 liter bottle through the bottom of a desk. (I had it under a desk to avoid damaging the ceiling tiles.).
You read that right... THROUGH the bottom of the desk. The bottom part is made of plywood and has a cubbyhole for books. The 2 liter bottle went THROUGH the plywood, splinters and pieces of wood exploded out of the desk. Empty 2-liter bottle.
So, I pointed out to my students that someone mentioned in class the video of the idiots mixing alcohol and ammonia in a 2 liter bottle and it exploding in the kids hand. I pointed out that suppose they threw it, it hit the ground, and the cap broke off instead - it could propel the 2 liter bottle right into their skulls. I think some of the kids thought the video was a great idea beforehand (assuming it didn't burst in your hand.) I think afterward, they saw how dangerous the pressure actually is.
btw, I had always wanted to see a CO2 tank get it's valve-stem piece knocked off, which allegedly would propel it through a cinderblock wall. I really don't need to see that happen anymore, now that I've propelled an EMPTY PLASTIC 2 liter bottle through plywood!! (albeit only 3 plies, but really... wow.)
So, in physics class, I'm doing my end of the year labs. Kids have already met the lab requirements, so the labs are completely fun, and mostly for review.
We're doing a lab where they design and test, make modifications (one of the standards is in engineering for science), etc.
They're building rockets, and using a 2 liter bottle for the engine - 1/2 full of water, and at 100psi. Heck of a lot of thrust from those things (video analysis calculated the acceleration at about 100 times the acceleration from gravity)
The conclusion of the lab is a contest - students have to launch a raw egg into the air using their rocket. Whoever's egg stays up the longest, and returns without breaking is the winner.
To make it fair, I added a pressure regulator so no one could exceed 100psi. I was adjusting it during lab time today (and I was also watching a small studyhall). Pumped a bottle up to 100psi with air only. Physics kids could hardly contain the laughter as they knew what a loud bang it was going to make as I launched the empty bottle under a desk. They knew the studyhall kids would jump out of their seats. (and, they did)
Well, now, imagine propelling an empty 2 liter bottle through the bottom of a desk. (I had it under a desk to avoid damaging the ceiling tiles.).
You read that right... THROUGH the bottom of the desk. The bottom part is made of plywood and has a cubbyhole for books. The 2 liter bottle went THROUGH the plywood, splinters and pieces of wood exploded out of the desk. Empty 2-liter bottle.
So, I pointed out to my students that someone mentioned in class the video of the idiots mixing alcohol and ammonia in a 2 liter bottle and it exploding in the kids hand. I pointed out that suppose they threw it, it hit the ground, and the cap broke off instead - it could propel the 2 liter bottle right into their skulls. I think some of the kids thought the video was a great idea beforehand (assuming it didn't burst in your hand.) I think afterward, they saw how dangerous the pressure actually is.
btw, I had always wanted to see a CO2 tank get it's valve-stem piece knocked off, which allegedly would propel it through a cinderblock wall. I really don't need to see that happen anymore, now that I've propelled an EMPTY PLASTIC 2 liter bottle through plywood!! (albeit only 3 plies, but really... wow.)
