system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: What makes a knife’s blade sharp?

What is so special about a sharp knife’s structure that makes it cut things easily?
gpt
Think of it like diving into water vs doing a belly flop. A sharp knife starts very thin down to a microscopic level and gradually gets wider causing matter it comes into contact with to part much like a dive parts the water. If the knife is dull it has flatness to the edge and the knife will resist passing through the matter just like a belly flop resists passing through water.