I genuinely thought the outside one would do it. 😂

@nargacugalover

3 ай бұрын

Same

@logiclrd

3 ай бұрын

When spinning at the same speed, the disc with the weight further out has more energy.

@Totaro77

2 ай бұрын

​@@logiclrdno

@logiclrd

2 ай бұрын

@@Totaro77 Explain yourself.

@rhen2572

2 ай бұрын

@@logiclrdit takes more energy to get it spinning but they have the same energy going down the hill. 🤦‍♂️

Fun fact, if allowed to continue rolling, the one with the weights around the outsode will roll for longer

@WissamSeif

2 ай бұрын

Yup!

@andybowes5163

2 ай бұрын

My first thought was that outer weights would sustain inertia! Physics is fun! Gyroscopic effects are greater with more diameter.

@WissamSeif

2 ай бұрын

@@andybowes5163 actually I might be wrong here. Since they both start with the same amount of energy, I think that they should travel the same distance

@andybowes5163

2 ай бұрын

@WissamSeif At the same rate of speed, after acceleration stops the larger diameter one has more stored energy. It would go farther. As far as side by side on the same ramp...that would be an interesting test! 🤔 If they arrived at the same stopping point at the same time that would be amazing!

@thirtykbc

2 ай бұрын

Conservation of energy

The weights in the middle would win it can accelerate faster because the weights have a smaller distance to travel around the wheel, therefore have less inertia to overcome.

@cameronvanatti6629

3 ай бұрын

I'm so glad I paid attention in school and actively sought out more information from many very trustworthy KZread channels we all know that are mostly science based, such as ASAP Science and Vsauce, and many science teachers that love teaching and science so much that they make videos to explain things for their students (in the case of sick days and substitutes) and leave them open to the public Because I knew right away and this isn't the first time I am learning about it

@heyheyjj

3 ай бұрын

But I think the one with the outer weights would have a higher terminal velocity rolling down an ramp because of its inertia, right? I wonder how to calculate when it would overtake the other one

@WissamSeif

3 ай бұрын

@@heyheyjj It shouldn’t. The disk with the higher inertia has to have more energy put into rotating it than moving it forward. The acceleration shouldn’t change, it’s constant, so the gap should just get further and further

@xaviermeyer660

2 ай бұрын

​@heyheyjj great question. I had to look up some formulas here. Terminal velocity is a function of weight\density, coefficient of drag, and cross sectional area. Therefore, in this rolling scenario terminal velocity would be equal. With the differences of inertia you would see the outer bolt disk travel farther if they started to slow down. If the ramp leveled off it would be harder to stop.

@WissamSeif

2 ай бұрын

@@xaviermeyer660 that’s not right my guy. Both disks start with the same energy, so they should travel the same distance, assuming that friction slows both of them down equally. I’m currently trying to test this out at a skateboarding park :)

Great Demonstration! 👌

Think of when an ice skater spins really fast, same concept

Really cool video!

I knew this from when I was a kid and played on the spinning shit and when you tucked yourself as close to possible you would spin faster so all that brain damage did help I guess

I was right! Good way to remember this is how when kids play on a merry go round, it'll actually start to spin quicker when the kids jump to the center. I used to do that when I was a kid all the time and loved it lol. It even works with only 1 person, but its even more noticeable with at least 3 kids

Great analogy for Gas engine vs Diesel engine

I knew which one is gonna go faster when Im thinking of it as a gear and the bolts placement is the size diameter of the gear in which the smaller the diameter having faster rotation than the other one with bigger diameter

Bro is underrated

Nice moment of inertia demonstration 👌🏼

Cool!!!

Чудово ! ❤

Another good example: Get an office chair (one that spins). Sit in it and start spinning, now stretch your legs outwards, you'll start spinning slow. Now pull your legs in and you'll spin faster.

The one with the weight near the middle has higher acceleration. However I believe that the one with the weight near the edge has higher top speed. So if they were to continue rolling the second one would catch up to and eventually surpass the first one.

I miss physics - mechanics! So much easier and intuitive than physics - waves/optics 😅

You would think because the weights are on the outside, gravity would pull down harder, creating a larger moment around the centre like a pivot, making it roll faster. Why is it NOT like that?

Creates less friction, and in the same way it has a center of mass that doesn't distort it's momentum, they might be the same thing too close to tell

Moment of inertia 😍

I thought the ramp would be longer and steeper, therefore I thought the one with the weight on the outside would win

@taylor....

3 ай бұрын

But the inside will still win. Coz of acceleration

@CartonOwO

3 ай бұрын

@@taylor.... I might be a tiny bit stupid, thanks :3

Pretty cool demo and you explain it like I'm slooooo.... which I am. Well, my boss def thinks so

that's why wheels are designed to have lugnuts in the center. Rotors would be too big and costly.

Parallel axis theorem. The one with metal cylinders on the outside has masses that are further away from its centroid thus a higher mass times r^2 value is added to the metal cylinders' moment of inertia, thus a higher net moment of inertia than the other object. Both objects have the same force/ torque on them(gravity on an inclined plane, same slope and same weight). The one with the higher moment of inertia will have less angular acceleration.

@miscellaneousaccount7203

Ай бұрын

Lol, my bad, didn't finish watching the whole thing. He ended up saying exactly what I said but better.

Witch one will roll the farthest?

My guess is the one where the bolts are on the edge

Learned this the hard way tried to do a one and a half and just thought I flip this hard to land on my feet so filled about as hard I could a bam landed on my belly because I didn’t tuck and I never tried again

I knew it wasn't a tie because he said those were two disks.

Keep that in mind if you want big tires on your ye ye truck. Costs more gas, wears down your breaks, and is less stable when you inevitably try to cut off the one vehicle on the road bigger than you 🚛🤬

More mass on the outside loses this one but would have more rotational force/torque.

Much like car wheels with the bolts towards the center of wheel and rubber tire on outside.

🕊️🧘🏼🌼Dao quickly come! ❤️‍🔥👻👻🙏

If there was a ramp then a long flat, the the one with the weights on the outside may catch up because it’ll be able to carry its speed further.

@WissamSeif

2 ай бұрын

If you ignore friction, they'll both keep traveling at the same speeds they left the ramp with forever and the slower one will never catch up. If they encounter the same frictional force, I think they'd end up stopping at the same place...? I'd have to think about it😄

What if the ramp were 10 times longer?

@WissamSeif

2 ай бұрын

The gap between them would just grow wider and wider. i.e the slower one will never catch up

@Dadstrength2.0

2 ай бұрын

@@WissamSeif thank you. I somehow thought that the one with the weights geared towards the end would eventually create more momentum. I was inaccurate in my assumption.

@WissamSeif

2 ай бұрын

It all comes down to energy. The outer-weighted one requires more energy to turn it, and so has less kinetic energy available to push it forward. It's a pretty neat problem; most people guess that the outside one is faster. I did too!

Now check out which one brakes faster.😅

Wouldnt the one with the bolts on the outside win if the track was longer?

@WissamSeif

2 ай бұрын

Nope!

It’s called moment of inertia, not inertia.

I thought about how tires are bolted on and took the inside one.. there has to be a logical reason for it

I learnt that on the playground

The winner here accelerates faster though if facing an uphill, it would lose it's speed/momentum quicker as well

@WissamSeif

2 ай бұрын

If they were going the same speed at the start of the hill, yes. The higher inertia one would have more energy to start with.

Thank

I thought it was matter of angular momentum.

¿Could it be said that the torque necessary to move the 'longer lever arm' of the wheel with the weights distributed further from the center is greater and therefore more energy has to be wasted to overcome said wheel's stationary resistance? 🤔

@WissamSeif

2 ай бұрын

The lever arms (radius of the wheels) are both the same. It does take more torque to spin the higher inertia wheel. The energy part is mostly correct, except that it's not just from rest where it needs more energy. As in, the slower wheel will never get closer to the faster one; it ALWAYS has to use more energy to turn itself than the other wheel, and so has less available energy to translate itself forward.

@mateobeccar2618

2 ай бұрын

@@WissamSeif Wow, thanks for the response. 🙂 I see. In all honesy, with "[...] longer lever arm of the wheel with weights distributed further from the center [...]" I meant the 'virtual' lever arm to be the distance from the center to the weights; shorter in the wheel with the weights clustered at the center and hence less energy-demanding when overcoming the stationary state. I suppose my assumption is still wrong, but just to clear my not so stellar wording. ¿Is the total energy finite, as in determined by the potential energy of the slope? In that case, the faster wheel will never be overtaken by the slower one, as a sizeable chunk of the available energy was already used to start the descent of the slower wheel. I'm sorry for all this. I just wanted to check how flawed my reasoning might be. I'm sort of inclined to compare this to a vehicle with bigger diameter wheels needing more torque to move/break inertia and hence being weaker, all things equal.

@WissamSeif

2 ай бұрын

I think we're saying the same things yea. I kind of want to expand on this experiment; try different shapes, sizes and masses..it's a cool problem!

Is there a difference, when both discs are in motion at the same speed (and you stop accelerating/putting in power - will one “role out” farther than the other? Would the same apply?

@WissamSeif

2 ай бұрын

The one with more stored energy will travel further. So, if both disks were rotating at the speeds, the one with the higher inertia will travel further because it has more stored rotational energy. This is the concept behind flywheels. Flywheels are designed to maximize their inertia (ie large diameter with more weight closer to the rim) in order to store more rotational energy to help better smooth out any oscillations of your power source.

@MichaelJ_

2 ай бұрын

@@WissamSeif thank you for your reply!!

So this would relate to sprockets on bikes, right? On bikes we can create similar gearing by running let’s say a 14/17 front sprocket combined with a 48/56 to get similar gearing. But I’m thinking the torque would be different, like less torque required for the 14t front sprocket. And more torque for the larger 17t front sprocket! Although mechanically each gear gives a similar speed?? Does that make sense, I’ve always thought the bike doesn’t really notice the difference but now I’m thinking it does..

@WissamSeif

2 ай бұрын

Hey man. Are you asking that if you have the same gear ratio b/t front and back but on different sprockets, what would be the difference in performance? Hmm…can you educate me on bikes a bit? I assumed that a 21 speed bike has 21 different gear ratios. Guess I don’t understand why you’d be able to achieve the same gear ratio on different sized gears, unless I’m misunderstanding something which I probably am.

I think over a longer distance the other one wins

Another explanation: both disks start with the same potential energy at the top of the ramp (same mass and height) and assuming they both experience similar friction, they will have the same kinetic energy right before they hit the bottom. As they're rotating, the total kinetic energy they have is split between linear and rotational kinetic energy, meaning the more energy it takes to rotate the disk, the less energy it can dedicate to moving down the ramp. The equation for rotational kinetic energy is .5Iw^2. I is inertia. The disk with the weights at the center is closest to a cylinder, so equation for inertia would be 1/2mr^2. The one with the weights toward the outside is closer to a ring, which has an equation of mr^2. Therefore the disk with weights toward the outside will have a higher inertia, meaning the rotational kinetic energy will be greater and the linear kinetic energy will be less. In conclusion: 🤓

THE AGE OLD DYNAMICS QUESTION

But you have to explain inertia: it's actually a function of resistance where there is greater resistance of the bolts on the outside

@WissamSeif

2 ай бұрын

Only so much you can explain in a one minute short 🤷‍♀️

@xyz.ijk.

2 ай бұрын

@@WissamSeif Itwasn’t a criticism, you said to put what we thought in the comments. I saw other people addressing inertia, so I took a step further.

If given the space each needs to reach the same speed, would they each impact a fixed obstacle with the same force?

@WissamSeif

2 ай бұрын

If I had an infinitely long ramp, the fast one will just keep getting farther and farther away, they'll never reach the same speed. I've thought about the force question; if you dropped them from the same height like here, they'd both hit the wall with the same amount of energy, but one has more velocity and the other has more rotatinoal energy..maybe worth a test!

@DelbertTritsch

2 ай бұрын

I wasn’t completely clear. I was imagining ramps of different lengths so that the impacts could occur at the same speed for each. I would think the one with higher rotational inertia that takes more energy to speed up would take more energy to stop. That actually makes sense the more I think about it. They stopped in this experiment with the same force but different speeds. If a longer track was provided for the one with higher rotational inertia, it would store more energy to reach the same speed as the other one that needed less track. A test would be cool!

@WissamSeif

2 ай бұрын

@@DelbertTritsch Ya if they both had the same speeds, the higher inertia one would have more stored energy so it should hit the wall with more force. I'm curious what happens if they hit the wall at different speeds but the have same total energy, like in this setup, because the faster one has more linear momentum and the slower has more angular momentum. My guess would be the faster one would have more of an impact

@DelbertTritsch

2 ай бұрын

@@WissamSeif An experiment sounds interesting.

Damnit I was wrong

I was wrong.

Cool demo and great explanation . But the camera and lighting is criminal

Make the ramp longer

@WissamSeif

2 ай бұрын

Workin on it :)

I knew the one with the bolts in the middle would get down first. Reason: anyone rerember those spinning posts youd play on in the park when u was a kid? Say around 2015 ish in Britain? Youd spin faster if you pulled youself as close to the centre. Amazing how playing and experimenting as children results in better understanding of the world around us eh?

“Thats just how it works…. Thankss

@WissamSeif

2 ай бұрын

I swear the internet has spoiled y’all so bad

@WissamSeif

2 ай бұрын

If you want a real understanding go watch some first year physics lectures, these are shorts bro..

@meatfat6991

2 ай бұрын

@@WissamSeif “these are just shorts” thankss

✨✨✨✨👍👍👍👍

So, 1 disk will get moving faster and the other will go a further distance.

@WissamSeif

2 ай бұрын

Hmm…why do you think that?

@jacobhargiss9909

2 ай бұрын

@@WissamSeif is that not the effect of one having more inertia than the other? When the ramp runs out and both are on flat ground, one will go through its stored energy faster than the other.

@WissamSeif

2 ай бұрын

@@jacobhargiss9909 if they were spinning at the same speed then yes you’re right, one would have more stored energy than the other. But both disks here started with the same amount of energy, so I’d think that they should actually travel the same distance

@WissamSeif

2 ай бұрын

@davemyers3553 ya I’m going to test this out at a skating park

If the track was longer. It would be opposite.

@WissamSeif

2 ай бұрын

explain..

@user-ug4ok3ov2t

2 ай бұрын

@@WissamSeif do I look like a dictionary to you?

Mgh=0.5Mv^2+0.5I(v/R)^2=cst So if I larger =>v smaller

@WissamSeif

2 ай бұрын

Bingo!!

Really nice demo but I hate the "thats just how physics works comment" it is a short video so I get it but this phrase is kinda upseting, 😅 sorry ptsd from bad teachers. Nice setup though!

I was wrong. Poop!

I really hate the explanation of "that's just how it works". No it fucking doesn't. There is an reason that we have well established why it works that way. Keeping it behind hand waving doesn't help anyone.

@WissamSeif

2 ай бұрын

So sorry to waste 60 seconds of your precious time buddy..maybe go watch some lectures on rotational physics if you want a better understanding but I’m sure you’ll find something to bitch about over there too

Sure, "that's just how the physics works"

@WissamSeif

2 ай бұрын

So sorry to disappoint u bro, go watch some lectures maybe

@nikhilkartha6157

2 ай бұрын

@@WissamSeif no no, I already saw the lectures on conservation of angular momentum. I already know torque is force times the distance from the revolute center. I was hoping though you'd have some layman's terms insight or maybe you'd draw some parallel to another thing like figure skater closing her arms for more speed or anything to do with merry go rounds. Anyway. This was a good video still. I enjoyed it. Thank you.

Now do the other way with the same initial speed

@WissamSeif

2 ай бұрын

Sure it would be flipped, but the higher inertia one would have more energy to begin with, so not a fair fight ;)

Thanks for nothing, basically saying just this is how it is

@WissamSeif

2 ай бұрын

😂😂sorry to waste ur time buddy

The outside will be faster.

@emariaenterprises

2 ай бұрын

Oops... I was wrong.

"that's just how the physics works" is such a bad explanation. Like you could approximate something comprehensible even if it's not perfectly accurate and it would be better than "trust me bro". Basically the nuts bolted to the outside have to travel a longer distance for a full rotation which slows them down

@WissamSeif

2 ай бұрын

Pal, KZread shorts are one minute long. You have a short amount of time to cram in the information that you want to convey. I used pretty much every second that I had and yet still get people like you to bitch about something. This was a simple, unoriginal experiment to demonstrate the concept of inertia. If you want a better understanding of rotational physics, then I suggest you go watch some first year physics lectures. Perhaps you'll feel a little more satisfied over there

This is rate of acceleration not inertia. Change the clip name and all good.

@WissamSeif

2 ай бұрын

uhh...their acceleration is a direct result of their inertia

@vitalie4650

2 ай бұрын

@@WissamSeif force of gravity is causing the acceleration (the slope). Inertia is after the slope finishes and objects keep moving.

Nope i guessed center cause more weight is concentrated in the middle..like he said higher and lower inertia..ive taken no physics🤣...it just seems obvious