- HOME
- NEWS
- SPORTS
- BUSINESS
- FYI/LIVING
- ENTERTAINMENT
- OPINION
- JOBS
- CARS
- REAL ESTATE
- RENTALS
- CLASSIFIEDS
- SHOPPING
- EXTRAS
Posted on Sun, Aug. 17, 2008 07:22 PM
The discus
More News
It sounds strange, but discus throwers are better off with a breeze in their face.
“To get the best throws, you actually want a slight head wind,” said UMKC physics professor Michael Kruger. “It’s completely counterintuitive. The reason is this: lift is determined by how quickly the air rushes by the discus. (With a headwind), the air is rushing past the discus a bit faster than if it were going in the other direction.
“You know that if you put your hand outside a car while it’s moving. You feel a force backward, but if you tilt it, there’s some force upward. That’s lift. The faster that wind is passing your hand, the greater the lift.”
There are three forces that affect the flight of the discus once it’s been released by the thrower: lift (keeping it aloft), gravity (pulling it down) and drag (slowing it down).
It’s worth noting that too much wind in a thrower’s face, and drag would be the dominant force instead of lift.
Physics also is involved before the discus is released, when the athlete does his/her turns in the ring.
“The turns do two things for them,” Kruger said. “By spinning around, they create rotational velocity. That will translate into extra speed for the discus when it leaves the hand. By rotating the body, they can actually make the discus go faster than if they don’t rotate.
“The other reason is when you throw the discus, by spinning (around) it makes it easier to impart spin on the discus itself.”
Spin is important for the stability of the discus. An object with spin will have angular momentum. With that, the object tends to want to stay in the same orientation it started.
Another factor on the flight of the discus is the length of the athlete’s arm.
Here’s an example of why: If you hold out your arm and spin around, your fingers will move faster than, say, your elbow. That’s because the fingers are farther from your body than the elbow, so they must move faster to keep up.
Finally, there is the angle of attack. This is the angle at which the discus is released. The optimal angle of attack is roughly 38 degrees. That will put the discus its best position for flight, taking advantage of lift.
“You want to maximize lift,” Kruger said, “and minimize drag.”
To reach Pete Grathoff, send e-mail to pgrathoff@kcstar.com
Posted on Sun, Aug. 17, 2008 07:22 PM
-
SERVICE TECHNICIAN
Superior Door Service, Inc.
-
ADMINISTRATIVE ASSISTANT
Chapel Hill Presbyterian Church
-
LPN'S AND CMT'S
Garden Valley Nursing & Rehab
-
Management - Sales
Confidential Company
@Nyx.CommentBody@