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Polar moment of inertia.

Resistance or lack there of to rotation or twist. In Boxster parlance refers to the center of gravity of the car and the relative location of mass about the CG. Since a major mass of the car (the motor) is located very close to the CG the boxster has a low polar moment of inertia (compared to a 911 for example where the motor is hanging out back behind the rear axle).

Low polar moment of inertia is "good" as it means that the car is more easily able to change direction. Low polar moment of inertia is "bad" as the car may change direction too easily i.e. spin.

High polar moment of inertia is "good" as the car is more "stable" because it resist changes in direction. High polar moment of inertia is "bad" as once the car starts changing directions it wants to keep changing direction i.e. spin.

On the other hand a polar moment could just be when you are really cold for a second or two.

:cold:

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OK thx...so then its true that round bottom women and Porsches really do make the world go round!

Thx for the lesson...

Jim

Polar moment of inertia.

Resistance or lack there of to rotation or twist.  In Boxster parlance refers to the center of gravity of the car and the relative location of mass about the CG.  Since a major mass of the car (the motor) is located very close to the CG the boxster has a low polar moment of inertia (compared to a 911 for example where the motor is hanging out back behind the rear axle).

Low polar moment of inertia is "good" as it means that the car is more easily able to change direction.  Low polar moment of inertia is "bad" as the car may change direction too easily i.e. spin.

High polar moment of inertia is "good" as the car is more "stable" because it resist changes in direction.  High polar moment of inertia is "bad" as once the car starts changing directions it wants to keep changing direction i.e. spin.

On the other hand a polar moment could just be when you are really cold for a second or two.

:cold:

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Well, it depends on the mass of the yoyo... if the yoyo is made of lead and the stick of bamboo... The kinetic inertia of the yoyo will be greater at the same angular velocity, thus having a higher polar moment than the stick.

This bring up to subject of gyroscopic precession, which can be easily felt in front drive car. When a mass angular velocity is changed (accelerated/decelerated) a force perpendicular to the monment of inertia and the rotational plan will be applied to the mass, the effect is a tendency for the rotating mass to tilt... wich explain the "coupling effect" you feel in the steering wheels. or why you need to give right rudder on an aircraft when you accelerate!

Jean-who-does-his-smart-***

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