Why did the feudal system rely on a high degree of local independence?

When many atoms are split in a chain reaction, a large explosion occurs. this is an example of what type of energy conservation

Suppose a wheel with a tire mounted on it is rotating at the constant rate of 2.15 times a second. a tack is stuck in the tire at a distance of 0.373 m from the rotation axis. noting that for every rotation the tack travels one circumference (a) find the tack's tangential speed. (b) what is the tacks radial acceleration?

How is zig zagging a form of acceleration?