# Discus

## Discus

A field sport where you throw a circular disk for distance

## Proper Release

Right-handed: clockwise

Left-handed: counter clockwise

## Motion in Discus

• Discus flies flat in the air
• Rotational motion is used to build up speed
• Linear motion from back of throwing circle to the front

## Air Resistance and Friction

• Air Resistance: When the discus is thrown, air resistance is always pushing against it.
• Friction: When the discus starts its descent, friction is acting on it as its on the floor.

## Air Path

When the discus is in the air, it should be flat so it can gain its maximum potential. As the wind increases, the discus gains greater air lift. Against the wind is better than with the wind, because this is forcing the air around the disc.

## Momentum

In order to gain more momentum, discus throwers wind up their upper body.

## 1st Law of Motion

Law of Inertia: an object in motion tends to stay at motion until an outside force is acted upon it
• When the discus is stationary, the forces acting upon it is balanced. When the disc is released from the athleteâ€™s hands, its forces become unbalanced because itâ€™s in motion. When it finally hits the ground, friction allows the disc to come to a full stop, making the forces balanced again.

## 2nd Law of Motion

Second Law of Motion: acceleration is produced when a force acts on a mass.

• The greater the mass of the object, the greater the amount of force needed to accelerate the object. A discus has a mass of 2kg for men and 1kg for women. In order to throw the disc, you have to apply force on it to make the forces unbalanced.

## 3rd Law of Motion

Third Law of Motion: every action has an equal and opposite reaction.

• When the thrower is spinning and slightly starts to push the disc out of their hands, the disc is also pushing back into their hand.

## Physic Principles

A discus is shaped like a heavier, weighted frisbee. The curved shape will provide the disc with lift and allow it to fly a considerable distance.

## Speeds and Velocities

An elite thrower will deliver the discus at the optimal angle with an approximate velocity of 20 mph (32 km/h). This will receive the additional effect of air speed passing over the discus, resulting in lift that will produce a throw that travels an extra 25 ft (8 m).

## Technology

The Olympics players often have a 3-D video analysis after they throw. This shows them what they are doing wrong and what they need to work on to get a farther throw. Younger players will also film themselves to see if they are doing everything correctly.

## Energy Conversions

• Potentialâ†’Kinetic: When an athlete winds up, they have potential energy. Then the energy is pushed through the legs, then to the hips, and though the arms flinging the disc into the air giving the disc kinetic energy.
• Mechanicalâ†’Heat: When the disc is travelling through the air, it is mechanical energy. When it hits the ground, there is friction, heat energy, stopping the disc completely.

## Conserved Energy

Energy cannot be destroyed nor created. Instead, energy is conserved. The shape of the disc allows it to smoothly glide through the air, conserving energy.

## Bibliography

"The Physics Involved in Throwing a Discus." LIVESTRONG.COM. LIVESTRONG.COM, 11 Aug. 2015. Web. 29 Oct. 2015.

"The Discus Paradox." Physics and Discus Throwing. N.p., n.d. Web. 29 Oct. 2015.

By, and Bruce Van Horne. Mastering the Grip, the Release and the Flat Sail in the Discus (n.d.): n. pag. Web.

"Discus Throwing â€” Digital Track and Field." Digital Track and Field. N.p., n.d. Web. 29 Oct. 2015.

"BIOMECHANICS." BIOMECHANICS. N.p., n.d. Web. 29 Oct. 2015.

"The Impact of Technology on Sport II." Google Books. N.p., n.d. Web. 29 Oct. 2015.

"Discus." - Strength. N.p., n.d. Web. 29 Oct. 2015.

"Law of Conservation of Energy Examples." YourDictionary. N.p., n.d. Web. 29 Oct. 2015.