Wonder if the result would be different if you could somehow get the force applied evenly across the surface.
this post was submitted on 11 Sep 2023
167 points (98.8% liked)
Gifs
1750 readers
1 users here now
A Community for people to create posts with GIFs or MP4s (hosted on external sites), or WEBPs (hosted on lemmy or on external sites).
founded 1 year ago
MODERATORS
It would flatten out against the surface and then break similarly but out to the sides
Yup, looks like it breaks because the string essentially cuts it in half
Watches 10 seconds gif "yeah, I know exactly what's going on here and will confidently state my incorrect opinion as fact"
But... You can see a divot in the center of the wheel where the string is making contact. It looks like it breaks apart because of that new weak point. It's not like I'm being an armchair physics professor, I'm making an inference.
What string? It's a water jet.
You know, I wasn't sure whether it was a water jet or not, since that's used to cut through STONE. So, it's likely that the wheel was being cut in half prior to it tearing apart.
The ones used to cut through stone and steel typically have diamond "sand" muddying the water. At least the one at my local machine shop does. I'm guessing the one in the gif is straight water.
I'd like to know how many rpms that is and the speed that equates to when it starts deforming and when it flies apart.
Based on 45k rpm mentioned in another comment and picking, idk, a 52mm diameter wheel (they range from 48-60) that's 163mm circumference.
45k rev/m x 60 m/h x 163mm/rev x 1km/1e6mm
= 440kmh = 273mph.
(I probably messed up something but idk)
Asking for a friend.
Literally the first two things that came to my mind lol, sad to see no one has an answer yet
Someone just answered. 45k rpm
Fake. It's obviously a bagel.
I hate when that happens
Honestly a mesmerizing gif...
Lots of heat here too I suspect. The deformation is going to be way easier with all that heat from the friction.
Didn't know they could expand like that
Only once though.
Somebody tell us about angular momentum vs centripetal force. I failed physics so I can't do it.
Angular momentum is a measure of an object's rotation around a point (#spin) 🌪️.
Centripetal force is the force that keeps an object moving in a circular path, always pointing towards the center (#holdingtight) 🎯.
One is about spinning momentum, the other about the force directing that spin.
In this example:
As you shoot the water jet at the skateboard wheel, you are continuously adding angular momentum to the wheel. This increases the wheel's rotational speed.
As the wheel spins faster and faster, the individual particles in the wheel experience a greater centripetal force, pulling them towards the center of the wheel's rotation. However, at the same time, due to the increased rotational speed, the particles also experience a greater centrifugal force (which is not a real force but an apparent force observed in a rotating reference frame), pushing them outwards.
At a certain point, this outward "force" (centrifugal effect) becomes too great for the material of the wheel to withstand, overcoming the cohesive forces holding the wheel together, and it starts to expand and eventually breaks.
This being said, I'm not sure if that's actually correct what I just wrote, so take it all with a grain of salt (as one should do anyway when reading something online...)
The way I think about it is that all the individual atoms of the wheel wants to move in a straight line. The only reason the wheel doesn't fall apart normally when it turns is that the material is strong enough to hold itself together. However as it spins faster and faster it requires more and more strength to keep itself together and at some point it moves so fast that the internal strength of the material is not strong enough to pull itself away from this straight line, which causes it to break.
Probably a good advertisement for Bones Reds too.
Best investment I ever made. Mfs are silky smoove
Heck yeah. I still have mine as backups for when my Super Swiss 6's start grating. Been years though, these bearings are made to last that's for sure.
I use Reds on my quad wheels. I just consider them as cost of buying new wheels because I’ll be damned if I use factory shit bearings. How are the 6’s treating you?
Sorry just saw this reply!
The SS6 bearings are insanely fast, and all my friends call them death traps as they can't even stand on the board. 10/10 highly recommended.