Question

When pizza dough is thrown/spun up into the air, what is the force that causes it to stretch out? And how exactly does it work? (Explain the physics principles involved)

Answer 1

Centrifugal force does not exist. There's a tangential acceleration along the side of the dough that's directed in a line tangent to the spin of the pizza, the reason the pizza doesn't completely tear apart is that there is also a radial acceleration created by the tension between the particles directed towards the center, also called centripetal acceleration. These accelerations are what produce the force since force is the product of mass and acceleration.

Answer 2

Without getting into the argument of whether or not centrifugal forces "exist," let's discuss acceleration. Whenever an object's velocity changes, it is a result of some form of acceleration - and remembering that velocity is a vector quantity with magnitude and direction, any change in either of these components is a change in velocity. When an object rotates along an arc, its direction is constantly changing, meaning its velocity is also constantly changing, meaning it is accelerating - but it is not necessarily changing speed.

Centripetal forces are associated with rotational motion, and as an object rotates along an arc, it is constantly undergoing centripetal acceleration perpendicular to the direction of motion at any point during the rotation, towards the centre. Think of a car going around a round-a-bout or traffic circle (or whatever it's called in your local region) - as it turns around it, its is always being accelerated towards the very centre of the circle.

If an object changes it speed while turning, then it is also undergoing tangential acceleration. Tangential acceleration is in the same direction of motion (i.e. perpendicular to centripetal acceleration), and the sum of the tangential (if present) and centripetal acceleration makes the total acceleration experienced by the object.