Q&A: If a trapeze artist rotates once each second while sailing through the air, and contracts to reduce her rotati

Question by Dirck G: If a trapeze artist rotates once each second while sailing through the air, and contracts to reduce her rotati
If a trapeze artist rotates once each second while sailing through the air, and contracts to reduce her rotational inertia to one fifth of what it was, how many rotations per second will result?

Best answer:

Answer by Dr Spock
The answer is: 5 rotations per second.

By “rotational inertia” you mean what is more commonly called the trapeze artist’s “Moment of Inertia.” Let’s call that MI.

Angular momentum is (MI)w, where ‘ w ‘ is the angular velocity. The principle in this problem is that angular momentum is conserved, unless some new torque acts on the rotating body.

So, if (MI)w is conserved, and MI DECREASES by a factor of 5, then w must INCREASE by a factor of 5.

Live long and prosper.

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