# Angular momentum vectors and frisbees

• mperkins01
In summary, the direction of the spin vector for a frisbee or gyroscope is a matter of convention and consistency. Both the angular momentum and applied torque follow the same convention, resulting in the same spin convention. This means that whether a person is left or right handed, they can achieve the same spin while throwing. Additionally, a flying ring like an Aerobie is designed to minimize the pitching torque and eliminate precession.
mperkins01
While working on shooting mechanisms for the 2013 FIRST Robotics Competition, our mentoring scientist noted that the direction of the angular momentum vector pointed down for our prototype shooter. So now we're debating whether the vector points up or down matters for the flight of the frisbee. I argue that it must be the same, since a left handed person can throw as well as a right handed person.

Which way a spin vector points is a matter of convention. See http://en.wikipedia.org/wiki/Right-hand_rule. As far as the maths is concerned, it doesn't matter which way you choose as long as you are consistent. For the flight of a Frisbee or a gyroscope, there are are two spin vectors of interest: its angular momentum and an applied torque. Using the same convention for each of those (and using the convention for direction of cross-product that matches the order in the equation) produces a resultant precession in the same spin convention.

mperkins01 said:
I argue that it must be the same, since a left handed person can throw as well as a right handed person.
or a right handed person can throw with an "outside" spin to get the same spin as an "inside" left handed throw.

For a frisbee, there's a downwards pitching torque during flight (due to center of lift offset from center of mass) that results in precession to the left or right. An Aerobie, which is a flying ring, is designed to eliminate nearly all of this pitching torque which mostly eliminates the precession issue.

## What is angular momentum?

Angular momentum is a measure of the amount of rotation an object has. It is a vector quantity that takes into account the mass, velocity, and distance from the axis of rotation.

## How is angular momentum related to frisbees?

Frisbees are an example of an object that has angular momentum. As the frisbee spins through the air, its angular momentum remains constant unless acted upon by an external force.

## What is the role of angular momentum in keeping a frisbee in the air?

The angular momentum of a frisbee is what allows it to maintain its spin and stay in the air. The spin of the frisbee creates lift and stability, which keeps it aloft.

## Can the angular momentum of a frisbee be changed?

Yes, the angular momentum of a frisbee can be changed if an external torque is applied. This can happen if the frisbee hits an object or is influenced by wind or other forces.

## How does the shape and weight of a frisbee affect its angular momentum?

The shape and weight of a frisbee can affect its angular momentum. A frisbee with a larger surface area or a heavier weight will have a greater angular momentum compared to a smaller or lighter frisbee, assuming they are spinning at the same speed.

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