Definition
A descriptive phrase referring to the fact that any point on a rotating body travels along a circular path, and the linear speed of that point depends on both the rotational speed (RPM) of the body and the radius of the point from the axis of rotation. Points farther from the center travel faster than points closer in, even though the entire body rotates at the same RPM.
Plain English
When something spins, every part of it moves in a circle. Parts near the outer edge cover more distance per turn than parts near the middle, so they move faster — even though the whole thing is spinning at the same rate.
Context Anchor
Seen in aviation discussions of turning motion, propellers, rotors, and other parts or aircraft motions that involve circular movement.
Why Pilots Care
This is why propeller and rotor tips are the speed-limiting part of the system. The tip can approach the speed of sound long before the hub does, which limits how fast a propeller can be spun before efficiency drops and noise, vibration, and structural stress climb sharply.
Analogy
Think of a running track. If two runners go around the track shoulder to shoulder, the one on the outer lane has to run faster to keep up, because their circle is bigger. A spinning blade works the same way — the tip is in the outer lane.
Grounding Statement
In circular motion, more rotational speed means more force is needed to keep the object from continuing straight ahead.
Intuition Check
Do not assume that doubling the rotational speed only doubles the force involved. In circular motion, the force needed can increase much more quickly than the speed increase feels.
Example Sentence 1
Because of the circular path at various rotational speeds along a propeller blade, the tip generates far more lift and drag than the section near the hub.
Example Sentence 2
The test rig moves the mass in a circular path at various rotational speeds to simulate flight loads.