Frisbee Physics

Frisbee Physics 

Frisbee flight is dependent on the properties of angular momentum. What angular momentum does for the frisbee is hold it in the same orientation in which it was launched. It does this by resisting the effects of torques and stabilizing the spin axis. If the spin axis is fixed, there is much less chance of the torque affecting the system.

The conservation of angular momentum states that the angular momentum of an object remains constant unless acted upon by a torque. In terms of Frisbee throws this is extremely important because a thrower can use the effects of torques to alter the actions of the frisbee and create different tosses. 

The clearest example of a torque changing the spin axis of a frisbee is the skip shot. The skip shot results only if the outer (away from thrower's body) edge of the frisbee makes contact with the ground. The frisbee is thrown at an angle toward the ground with a relatively large amount of angular momentum. The frisbee jumps up because a slight impulse provided by the torque from the ground is imparted onto the frisbee. This causes the frisbee to recoil by changing the location of the spin axis. The spin axis is tipped backward (towards the thrower) and the frisbee's orientation then points above the horizontal (ground) and it sails up into the air with it's new direction.

Bernoulli's Principle

When a fluid flows, the pressure decreases while the flow velocity increases.

Bernoulli's Principle explains why the frisbee is able to stay afloat as it soars through the air. A frisbee has a curve that creates a unique shape that induces air to pass slightly faster across the top surface of the frisbee than against the bottom surface. The difference between the upward and downward pressures creates a net force upward, called lift. Lift keeps the frisbee in horizontal flight.