A very close shave

[Ed]

[Fletcher]

Greendoor .. Nick has given you what you/we desired, that is a simple combination of the basics of the atwoods & cylinder & sphere(s) experiments that shows an attached drive mass falling on a flywheel [atwoods] & a mass being raised quickly via a tether [cylinder & sphere], in the process stopping the flywheel.

The bike wheel has very little mass & inertia of its own - you want him to alter the experimental setup to something closer to peq. atwoods by making the flywheel more massive with symmetrically placed rim masses - you acknowledge that this will slow the descent rate of the attached drive mass giving more time - yep, that's what will happen.

In order for peq. theory of transferring & using momentum to hoist the flung mass highest then the same conditions should apply except the flywheel has way more mass - according to your camp that should see a substantial rise in height of the flung mass - in fact peq. was talking about energy increases of not just near or beyond unity but in the thousands of percentage with heavier flywheels [could be scaled according to resources].

I suggest that Nick increase the attached drive mass first - see if there is a gain in height - there should be, as the descent will be faster [with the current flywheel mass & inertia] - then try the same increased drive mass but this time with increased flywheel mass & inertia - according to you this will slow the rotation & then transfer an even greater portion of momentum as velocity to the flung mass - we should see a greater height achieved than with the light flywheel ?

I would suggest that the more massive flywheel test would result in a slower rotation [giving more time] but no increase in height obtained - that would be obtained by steadily increasing the drive mass & NOT the flywheel inertia.

Isn't that the wonderful thing about simple experiments such as Nick has shared - anyone can build one & actually get some data to back up their favourite theory ?!

P.S. yes, I've read the 'nutters' pages a few years back - wasn't too impressed, sorry.

[Grimer]

From a 12 start with 2 x 50 grams on a bike wheel, I get a averaged rise at 6 of over 15% of the total mass. Don't believe that ? Nor do I. http://www.youtube.com/watch?v=377_XEknNKg and please tell me where I'm wrong :-) Otherwise I shall have to build a wheel contraption which takes advantage of all these dirty little mechanical tricks and just keeps on running. That would be a real hassle.

Yeah, I know, another dumb bike wheel experiment. But it's all adding up very fast.

Good fun, anyway.

I've only just started reading this thread but I don't seem to be able to open the video. It says it's private or something.

bump

[Fletcher]

P.S. greendoor .. you could build something closer to the atwoods combined with nick's tether arrangement - just have two grooved wheel rims bolted together - sling a rope over one with equal masses hanging below, as per atwoods - attach a drive weight to one of the hanging masses - have as much mass attached to the bike wheel as you want to give it greater mass & inertia.

On the second grooved wheel duplicate nick's tethered mass falling & releasing from 12 o'cl thereabouts.

This is a closer setup to peq.'s two tests.

I know you ride bikes & probably do some fishing living in canterbury so you'll have line & sinkers.

[Mark]

Glad I'm not the only one that thought of Wallace and Gromit (on seeing the topic title).
;-)

[nicbordeaux]

Brilliant Ed, bought a big grin this end. It's all there, the perfect parody ;-)

[nicbordeaux]

Abducted by aliens ?

Bit of a mystery, a lot of the big names who usually chime in aren't here. Aliens ? Running to the patent office LOL ?

Sorry Grimer, the vid was made "private" because enough people from this forum I guessed had seen it. If nobody can pass you a copy, I think I can send you a one time private access url, but you may need a youtube acount to use it. Not sure.

[Wubbly]

Nick, your video was so inspiring I had to try to duplicate it. Here's a video of my attempt: http://www.youtube.com/watch?v=bwCZhoMFoFU

My experiment is a variant of yours. A circular sheet of 1/2" plywood was used and it was balanced (with washers on a bolt) prior to the addition of the two extra masses (m1 and m2). The two extra masses (one tethered and one attached to the plywood) consist of rollerblade wheels with their bearings.
Heights h1 and h2 are referenced to the center of the rollerblade wheels. Height h3 is the height the tethered mass must exceed in order to claim energy gain.

h1 = mass1 at 6 o'clock position: h1 = 0.0 [m]
h2 = mass1 at 12 o'clock position: h2 = 0.543 [m]
h3 = h1 + (2 x h2) + radius of rollerblade wheel = 1.127 [m]
In the experiment, black tape is placed at height h3 for easy verification of energy gain.

m1 = rollerblade wheel 1 = mass attached to plywood: m1 = 0.107 [kg]
m2 = rollerblade wheel 2 = mass attached to the tether: m2 = 0.106 [kg]

mass of the string is less than 1 gram
mass of the plywood with bolts and screws: 1.865 [kg]
mass of the steel plate attaching the plywood to the axel: 1.107 [kg]
mass of axel: 0.279 [kg]

Nick, Unfortunately I was unable to duplicate the results of your experiment. In my experiment, ignoring the mass of the axel, the mass of the "cylinders" part has a total mass of 3.079 [kg], and the mass of the "sphere's" part was 0.106 [kg]. The final potential energy in my experiment was slightly less than 100 percent of the initial potential energy as can be seen by the height that m2 reached relative to the black line.

However, I was able to get the tethered mass m2 to rise above the black line by doubling mass m1 to 0.212 kg. Nick, if there was experimental error in your setup, it could be due to the mass of your lead weight being greater than the mass of your bouncy ball. If they are both exactly 50 grams, then your results are quite interesting.

Nick, I just watched your mad math video. What are you doing to get yours to work?

[ovyyus]

Nice video Wubbly, thorough. The music has left me feeling soothed, curious, and slightly melancholic.

What is Nick doing differently?

[beapilot]

Nick, your video was so inspiring I had to try to duplicate it. Here's a video of my attempt: http://www.youtube.com/watch?v=bwCZhoMFoFU

My experiment is a variant of yours. A circular sheet of 1/2" plywood was used and it was balanced (with washers on a bolt) prior to the addition of the two extra masses (m1 and m2). The two extra masses (one tethered and one attached to the plywood) consist of rollerblade wheels with their bearings.
Heights h1 and h2 are referenced to the center of the rollerblade wheels. Height h3 is the height the tethered mass must exceed in order to claim energy gain.

h1 = mass1 at 6 o'clock position: h1 = 0.0 [m]
h2 = mass1 at 12 o'clock position: h2 = 0.543 [m]
h3 = h1 + (2 x h2) + radius of rollerblade wheel = 1.127 [m]
In the experiment, black tape is placed at height h3 for easy verification of energy gain.

m1 = rollerblade wheel 1 = mass attached to plywood: m1 = 0.107 [kg]
m2 = rollerblade wheel 2 = mass attached to the tether: m2 = 0.106 [kg]

mass of the string is less than 1 gram
mass of the plywood with bolts and screws: 1.865 [kg]
mass of the steel plate attaching the plywood to the axel: 1.107 [kg]
mass of axel: 0.279 [kg]

Nick, Unfortunately I was unable to duplicate the results of your experiment. In my experiment, ignoring the mass of the axel, the mass of the "cylinders" part has a total mass of 3.079 [kg], and the mass of the "sphere's" part was 0.106 [kg]. The final potential energy in my experiment was slightly less than 100 percent of the initial potential energy as can be seen by the height that m2 reached relative to the black line.

However, I was able to get the tethered mass m2 to rise above the black line by doubling mass m1 to 0.212 kg. Nick, if there was experimental error in your setup, it could be due to the mass of your lead weight being greater than the mass of your bouncy ball. If they are both exactly 50 grams, then your results are quite interesting.

Nick, I just watched your mad math video. What are you doing to get yours to work?

Wubbly,

You have missed 2 major important parts of Nick's wheel to get it to fling up. The release point on Nicks wheel is extremely important. Second, you see more of the weight falling downwards on his wheel further than the bottom wheel. The point of the release point is to increase the force. When the string goes off, the offset weight inertia/momentum transfers into the string by "pulling" it.

It is a slightly complicated thing to understand but the simplest way is to get a pendulum. Gradually pull on the pendulum and release and repeat. The more you do, the higher it goes because you keep pulling it.

Thanks for making the video! I loved the music.

Joshua

[jim_mich]

What is Nick doing differently?

Two things are different...

The sheet of plywood is heavier than a bicycle wheel.

The radius of gyration of a solid disc is about 0.7×R while the radius if gyration of a bicycle rim is very close to 1×R.

Both influence the peak rotation speed and the stored momentum at the time the weight releases from the rim.

The difference is in the blasted bothersome little details.

[ovyyus]

Jim, my bike wheel replication attempt behaves similar to Wubbly's demonstration. IMO, the difference must be due to some other bothersome little detail we're not yet seeing.

[Trevor Lyn Whatford]

Hi Nick,

Nicks quote,Abducted by aliens ?

Bit of a mystery, a lot of the big names who usually chime in aren't here. Aliens ? Running to the patent office LOL ?

Be carful If you insult Mum & Dad you insult me!

Did I miss anything as I was just running back from the Patent Office you should of seen the que!

The truth is I am Allergic to algebra I get nausea and headaches!

The real truth is you are doing a good job so good luck,

When you said big names I thought you meant me (Trevor Lyn Whatford), sorry!

Regards Trevor

[nicbordeaux]

Wubbly, your building skills amaze me. Can't put it better than that ;-)

I think both Jim and Joshua are right, but that isn't the whole story as I imagine I might possibly be beginning to understand it...

http://www.youtube.com/watch?v=jsG7_6O-yEg is a very short vid, low quality as i don't have good cam and wwm is 25 fps whether you choose pal or else.

What the slow part of the vid shows is the following sequence of events, if you look very, very carefully (and probably if you've physically seen the gizmo and the original footage which is higher quality, when you record under wmm you loose a lot): At release ball is 1 cm from weight. Ball accelerates towards weight which is moving slower. Ball lifts off wheel rim slightly without hitting weight. Weight accelerates to faster speed than ball and moves away. Ball catches up, moves down to rim and impacts weight. Ball trajectory is modified by riding off edge of weight and being released.

That is some very complex stuff which would (does) need very hi-res filming in perfect light to ID. So it looks like a pretty mad sequence of collisions, different fall rates, fall paths.

So to answer Ovyyus, in "what are you doing different?" : superball is the first logical point I can identify. And maybe hammer a little lip into the back edge of your weight ?

Do you play golf ? Is there anywhere you can steal a golfball ? Say one of those that is designed to get get maximum distance by having special dent patterns (coriolis ?).

This isn't afaik anything to do with energy "gain", eg zero point and rubbish like that. It's simple mechanics. If it's height we're looking for, for a given weight, we could probably build a wheel which releases a frisbee, who knows ? In fact, it might be a darn sight better, because then it would (hopefully) be entirely duplicable, all parameters being known.

Thx everybody.

[daxwc]

I think the super ball is bump drafting the weight, it is the rolling start and the elastic impact of the super ball off the drive weight that accounting for his height gain.