system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why do some things cut better with a serrated knife and others with a straight blade?
gpt
It actually depends on a few factors. What you are cutting, the type of knife or blade you are using, and other things like temperature of the knife and the object you are cutting.

The biggest determiner, is the thing you are cutting. Soft, malleable things like loaves of bread, or very loose meat, don't cut well with a sharp edge because you don't have enough tension in the material you are cutting to press against the blade and create an even cutting surface. Tomatoes and Bread are excellent examples of this. Only the sharpest of sharp knives can even hope to cut cleanly and evenly through some breads and most tomatoes without issue or mushing.

Serated blades, seek to change this by adding in the serrations, tips and points that act to tear and have sharp points that press into what you are cutting and pull small sections, like a saw blade and tear bits and pieces instead of cutting cleanly and straight through.

Very, Very hard things also have the same problem, like bone or frozen foods. The ice makes the object to cut so hard and dense, that a sharp knife is almost useless. A serrated knife on the other hand, can cut by ripping and tearing its way through the object where a standard blade could never perform.