system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: how does a blender, with fixed blades, perform different types of mixing by just varying the blade speed?

The only difference between frappe, mix, etc is just how fast the blades spin?  Is there any other physics going on here?
gpt
As well as the speed of the blades, the machine can also pulse - a quick burst of high speed, followed by a pause to allow the mix to rest and to settle. This requires a small computer to run it, but micros are cheap these days - much cheaper than the triac required to change the motor speed.

More expensive blenders have higher speed motors. A cheap blender might have a motor similar to that used in an old-style multi-speed fan - which has 3 or 5 different speeds depending on how the coils are connected via a multi-way switch. Or it might have a motor like a modern fan, which is speed controlled using a circuit like a light dimmer. A better blender will be controlled with a synchronous motor, driven by an inverter circuit as used by modern air conditioners. This allows the motor to be driven at any speed, even backwards, or to stop dead. This allows the makers to design all sorts of drive patterns to do anything. It's all bells and whistles, made possible by a slightly more complex circuit, with a few more expensive components, and a more expensive motor.