Why Does Balloon Volume Decrease with Liquid Nitrogen?

[TheLil'Turkey]

50 minutes into this video the professor puts a balloon into liquid nitrogen that's about 1/4 of the room temperature, but its volume decreases to much less than 1/4 of its original volume. Why?

Right after the balloon demo, he talks about tennis balls. Why if you open up a can of tennis balls, don't play with them for a few days, do they become useless? And how does this relate to whether the pressure in the sealed can of tennis balls was less than or greater that 1 atm?

 

[TheLil'Turkey]

50 minutes into this video the professor puts a balloon into liquid nitrogen that's about 1/4 of the room temperature, but its volume decreases to much less than 1/4 of its original volume. Why?

Right after the balloon demo, he talks about tennis balls. Why if you open up a can of tennis balls, don't play with them for a few days, do they become useless? And how does this relate to whether the pressure in the sealed can of tennis balls was less than or greater that 1 atm?

I figured out the bolded! It's because a large percentage of the air in the balloon condenses at such a low temperature.

I still have no idea about the 2nd question though. Please watch the video starting at the 51:30 mark to hear it.

 

[James Leighe]

some tennis balls are pressurized and the pressure leaks causing them to lose bounce

see: http://www.livestrong.com/article/402536-do-pressureless-tennis-balls-hit-the-same-as-regular-balls/

 

[TheLil'Turkey]

Thanks James. I now understand all the puzzles that are given at the end of the 1st semester MIT physics lectures. I highly recommend the lectures to other beginners.