chrishysell
* Ace Member *
all of my discs, including my putters, drivers and midranges, travel around 73mph every day.
-
Discover new ways to elevate your game with the updated DGCourseReview app!
It's entirely free and enhanced with features shaped by user feedback to ensure your best experience on the course. (App Store or Google Play)
How fast (in mph) do discs travel?
- Thread starter jchoate7
- Start date
There's no way the total kinetic energy increased, though I would believe that some energy transfers from linear movement to rotation. My guess is that the sensor was reading the change as the disc moved from rotating around a point at the edge of the disc (where the hand grips the disc) to rotating around the center of gravity of the disc, a rotational sensor would read that change as some kind of acceleration.
I'd guess than an OH throw goes through multiple stages of acceleration, it's constantly changing velocity as it changes direction rolling through the air, decreasing in 'speed' as it reaches the apex and then increasing 'speed' as it plummets to earth in free fall in its most aerodynamic orientation. Similarly as a ball tossed straight in the air slows down, stops, reverses direction, then accelerates towards the earth. Or a high stall hyzer that slows to a stop before fading and crashing to earth.
That is an interesting thought. The shift of the disc's rotation from around the fingertips to the center of the disc would happen in a linear direction. If you hold on tight enough on release, the center of the disc would be ahead of your fingertips which means that the shift would happen in a forward direction from your hand.
Could this shift in the center of rotation have an impact on the linear velocity of the disc? Its over my head for sure. But it brings up a point that there are a lot of variables involved in the motion of the disc to dismiss the idea that it could accelerate briefly after it leaves your finger tips.
- Joined
- Nov 2, 2008
- Messages
- 22,046
Didn't read all that, but my guess would be that a disc could increase rotational acceleration after stabilizing it's center of gravity if there was wobble which is likely. That doesn't mean the disc will accelerate speed though because it's losing linear energy fighting drag forces stabilizing itself.
The thing is though, no matter what the total amount of energy in the system can't increase after you stop propelling your disc. I'm fully prepared to admit I don't know enough about disc flight to say exactly the relation between the rotational and linear portions of the disc flight, but that doesn't change fundamental laws of physics that say the disc is losing energy overall once it is out of your hand (barring something strange like throwing straight downhill with an 80mph tailwind).
I guess that is why I am questioning your logic. The laws of physics don't mention anything about your hand. Energy is lost when there is no force being applied to the object. The rotation of the disc is a force within itself and you mentioned above that you don't know much about the relation between rotational and linear portions of the disc flight.
If you look at the graph that I mentioned, there is a huge spike of angular acceleration at the point of release. There is a lot of energy being transferred within the disc and that energy doesn't stabilize instantaneously.
- Joined
- Nov 2, 2008
- Messages
- 22,046
I'm guessing it takes 0.4sec for the center of gravity to stabilize. We are throwing the edge of the disc almost as if it were a hammer. The center of gravity of the disc shifts during the throw. The leading edge the disc with the mass/cog is moving faster than the handle/hand and oscillates until it's cog stabilizes. The cog never accelerates after release.
I think you're still missing my point. I said that there are many things going on, so it's entirely possible that some amount of angular acceleration happens. That energy has to come from somewhere, which likely means a loss of linear momentum as the disc's center of rotation shifts. The total amount of energy in the system absolutely cannot increase without an outside force acting on it, the energy can only be transferred to different parts of the system (angular and linear movement in this case).
theeterrbear
Par Member
No, the graph doesn't show that. You can see the nutation of the disc in the neat little wave that is created, which is what we refer to as wobble, but that is the only thing after the throw. The steep drop off on Figure 11a is the instrumentation no longer taking data. Read the caption for Figure 11. From it:
Looking at Figure 11a there are four distinct sections. The first section is from t=-1.00s to t=-.70s. This can be interpreted as before the throwing motion, when the disc is more or less at rest and not experiencing any acceleration. Notice how the graph is flat and at a certain level. From t=-.70s to t=-.10s the disc is being accelerated through the throwing motion. I am being more liberal in considering what is the throwing motion here, including the acceleration up to the level 2g that caption states. This is visible in the graph as it leaves the established baseline. The third section is the obvious spike in acceleration from t=-.10s to t=0.00s (the point of release). The fourth section is after the release, from t=0.00s to t=.40s when it appears that data is no longer being collected. Aside from the wave cause by nutation, or "wobble", the graph returns to the established baseline meaning no acceleration.
Any other questions? The various graphs support the laws of physics as we know them, and the only acceleration the disc experiences after leaving the hand is the negative acceleration ("deceleration") from air resistance.
Thanks, that makes sense. I could think of a lot more questions. However, 4b does a good job of showing the linear negative acceleration of horizontal velocity. Not a lot of data for the first .5s but enough for me to stop wanting to think about it.
KniceZ
Double Eagle Member
Darn - I was hoping that Mocheez had finally discovered the answer to the long sought after perpetual motion machine. Science has once again gotten in the way of our hopes and dreams. Thanks for the laughs!
I wish I could find the link to the video of the guy throwing the disc all the way around the world.
I'll probably not be as good as theeterrbear or mashnut but I feel compelled to pile on with a some quick comments:
- Yes there's all kinds of forces acting on a disc after it has been released (gravity, aerodynamics, gyroscopic, wind) that cause accelerations; some negative some positive.
- These forces mainly impact the velocity vectors direction.
- With the exception of maybe extreme tail wind or gravity on extreme down hill throws none of these forces can overcome the main decelerating force of aerodynamic drag.
- So disc speed is maximum at the moment of release.
- The discussion of angular momentum and linear motion are the key to snap. Brad Walker talks about this disc pivot in his videos about creating velocity at the moment of release.
I wish I could find the link to the video of the guy throwing the disc all the way around the world.
I'll probably not be as good as theeterrbear or mashnut but I feel compelled to pile on with a some quick comments:
- Yes there's all kinds of forces acting on a disc after it has been released (gravity, aerodynamics, gyroscopic, wind) that cause accelerations; some negative some positive.
- These forces mainly impact the velocity vectors direction.
- With the exception of maybe extreme tail wind or gravity on extreme down hill throws none of these forces can overcome the main decelerating force of aerodynamic drag.
- So disc speed is maximum at the moment of release.
- The discussion of angular momentum and linear motion are the key to snap. Brad Walker talks about this disc pivot in his videos about creating velocity at the moment of release.
I guess all that cheese-eating increases the overall momentum-mass of Wisconsinites, so God gave them different physics to even out the playing field. :\
Ha ha, I will keep looking and let know if I find it. Although, I was never claiming perpetual motion, just a very brief amount of accleration after the release.
I am lactose intolerant, maybe a well timed release of gas is the missing link that I am searching for.
- Joined
- Jul 29, 2009
- Messages
- 15,770
Pulled from a different thread...
This discussion didn't belong in the thread I pulled it from.
You're gonna hate me, but that example assumes a frisbee (or disc) falls at 9.81 m/s^2..... true if you drop it. Not true of a disc that's thrown with spin beacuse of the lift/glide. It behaves more like a wing. I'm not saying gravity isn't pulling downward on the disc with a force of 9.81 m/s^2 x the mass of the disc... it does. But that doesn't mean the disc falls at a the constant acceleration of objects in free fall or typical projectile motion (e.g. bullet, ball, other object that has negligible wind resistance to falling) . The net downward force on the disc is less due to lift. If it were not so, you'd be able to throw a ball a silimarly to a idsc, and they would fall at similar rates... but that doesn't happen. A thrown ball falls with little resistance. A thrown disc falls slower, because of the resistance.
That;s why discs stay aloft longer than balls thrown on a similar trajectory.
The linked article simply does not account for all the forces acting on a disc. Don't beleive me? Drop a disc from chest high at the same time as thrown flat from chest high... dropped disc will hit the groun first. One disc has glide, the other don't.
This discussion didn't belong in the thread I pulled it from.
You're gonna hate me, but that example assumes a frisbee (or disc) falls at 9.81 m/s^2..... true if you drop it. Not true of a disc that's thrown with spin beacuse of the lift/glide. It behaves more like a wing. I'm not saying gravity isn't pulling downward on the disc with a force of 9.81 m/s^2 x the mass of the disc... it does. But that doesn't mean the disc falls at a the constant acceleration of objects in free fall or typical projectile motion (e.g. bullet, ball, other object that has negligible wind resistance to falling) . The net downward force on the disc is less due to lift. If it were not so, you'd be able to throw a ball a silimarly to a idsc, and they would fall at similar rates... but that doesn't happen. A thrown ball falls with little resistance. A thrown disc falls slower, because of the resistance.
That;s why discs stay aloft longer than balls thrown on a similar trajectory.
The linked article simply does not account for all the forces acting on a disc. Don't beleive me? Drop a disc from chest high at the same time as thrown flat from chest high... dropped disc will hit the groun first. One disc has glide, the other don't.
Last edited:
Mabuku1
Double Eagle Member
shouldn't this thread belong in the equiptment section?
- Joined
- Dec 19, 2009
- Messages
- 6,855
Things don't always fall in their most aerodynamic orientation. Even when they are not spinning.
They "want" to fall in the stable orientation. For example, a bullet (once it loses its spin) will fall on its side, not nose down.
I saw it on Mythbusters. They had it in a vertical wind tunnel.
The bullet in the wind tunnel on mythbusters tumbled, it never fell in a single orientation. A disc would likely do the same thing, tumble and flip in a relatively random way.
Similar threads
