The Shorter the String, the Faster It will Turn

Let's take a look!

Watch the video on YouTube.

What kind of experiment is this?

Experimental procedure and explanation:

• Tie a ball to the center of rotation of a turntable with a string. The string length should be adjustable.
• “Angular Momentum” is a property that shows the strength (magnitude) of the rotation.
  (Angular Momentum) = (Object Mass) x (Radius) x (Velocity)
• When the angular momentum is constant, the speed is inversely proportional to the radius (law of conservation of angular momentum).
• In this experiment, we see that the shorter the string gets, the faster its velocity becomes, and vice versa.
• Figure skaters use the same principle. Spreading his or her arms will make the rotational speed slower, while pulling in arms and narrowing down the body (concentrating the mass on the center of rotation) will make the skater rotate faster (law of conservation of angular momentum).

[Keywords]	Law of angular momentum conservation
[Reference]	“The Wonders of Flow,” Japan Society of Mechanical Engineering, Kodansha Blue Backs pp. 54.