Liquid Nitrogen and the Banana

What happens when you put a banana into liquid nitrogen? Well… lets see:

(this definitely provided a nice distraction from the afternoon laboratory session biggrin.gif )
OK, so that’s cool.. but why does freezing a banana make it so brittle? Well… bananas have a large water content. As the banana is frozen this causes millions of tiny ice crystals to form. These form in many different spots and aren’t very well aligned (this is called a grain boundary). The presence of many weak boundaries makes it very easy to shatter the banana. A good analogue is to think of ice. A big block of solid ice (so one large crystal) is much easier to break up than a bag of ice cubes that are all stuck together (if you don’t believe me go give it a go!). Also, the freezing causes damage to the cell walls of the banana, making them much weaker than normal (and thus a reason why films likes Demolition Man will never happen… unless we make some massive progress in science).

Advertisements

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s

%d bloggers like this: