I love Flipping Physics. My Physics AP teacher told me to drop out of his class when I scored around 65/100 in the first test. He said, "Physics is not for everyone" or take it in college. Then I found Flipping Physics. I worked hard and watched Flipping Physics videos and took notes. I am now scoring on an average above 94 /100. Thank you Flipping Physics.
ur amazing !! i discovered this channel yesterday while i was studying mechanics and i've already watched 7 or 8 videos maybe lmao. cant stop, the way u put things it makes them look soooooo much easier. big thanks, luv
I am so sorry that ı was late to find this channel. It is literally awesome. I wish there would be more videos. Quite helpful. Thanks a lot. I could not finish my project without this video.
This helped make moment of inertia actually make sense!! When he said "wait that was too fast" I was like wow facts I am still lost, AND THEN HE EXPLAINED IT PERFECTLY- THIS MAN IS A PHYSICS GOD THANK YOU FOR ALL YOU DO.
This is extremely similar to the demonstration Professor Walter Lewin did for Physics World in July 2014. The biggest different is you provided a far clearer explanation coupled with simple and elegant mathematics that allows people to understand the theory as well as giving people the power to predict how objects will behave in similar experiments. No calculus required 👌
Another great video. I love your videos as it shows students how to approach and think about the question using the knowledge learnt before solving it.
I find this explanation using energy is the easiest to understand. The problem I had was trying to understand how this works in terms of forces. It was clear that an object with a higher coefficient for the moment of inertia (the X value in this video) must have a larger force of static friction pointing up the incline compared to one with a lower value of X. But how does having the mass be more concentrated further from the axis of rotation lead to a larger force of static friction? It took me a while to get my head around it to get a more complete picture of what was happening, and it's an explanation I have never seen as this energy explanation is usually the one people go for.
In our assumptions, by definition the the coefficient of static friction is as large as you need it to be, because it is a given that the object rolls without slipping. Concentrating the mass toward the outside, means that the traction has a larger burden to cause a torque about the center of mass, to get the same angular acceleration. No other force causes a torque about the center of mass than the traction.
@@carultch I understand that we can assume that the coefficient of static friction is as large as we like to ensure no slipping, but my point was about what the force of static friction (or traction) is for any given situation. So for a ring and a coin of the same mass, size etc, we know that the force of static friction which provides the torque and thus angular acceleration is larger on the ring than the coin, even if the coefficient for the static friction is the same for both. This coefficient determines the maximum available force of static friction, but it's the coefficient for the moment of inertia that determines the actual force of static friction which occurs for any given situation. The ring will accelerate slower than the coin, even if all other properties (except the MoI coefficient of course) are the same for each. How this happens as a result of a different mass distribution is what I didn't understand and I find most others don't either.
*Looking at the question before answer is shown* I think the solid sphere will roll first because of its inertia compared to others *After watching the video* yah so I was basically right, I just forgot to include the Important pieces in my answer such as the size of the fraction and also the inertia's relations to kinetic and potential energy
a very interesting result to all of this is that The Final VELOCITY is NOT Dependent on the MASS or RADIUS of any of these Objects.. The Final Velocity is = the Sqrt ( (2gh)/(1+X)) where X is the Factor in front of I= Xmr^2 .... Imagine that??
I wish I could claim credit for that. I think it is just blind luck. Soon enough your class will be ahead of the videos I am making. (My pace is actually slower than yours.)
Considering Dan Fullerton has already done many AP FRQ solutions th-cam.com/users/FizziksGuyvideos , I don't think it is the best use of my time at this point. Y'all will learn more from specific examples like these. My goal is to make a video for every topic in the AP Physics 1 curriculum.
Hi! I love your videoes. They are extremly helpful. I have one question. Does the objects in this experement have the same mas? Bc if the hoop has much less mas than the spheres, wont it then have a lower inertia bc there are less masses to sum up, if that makes sense. Bc inertia is the sum of all the masses times radius squared?
Hi my son is in physics and doing a presentation asking me for hallow and solid balls. I googled and this video came up and it sounds like exactly what he is planning to do. Where can I purchase those spears ? Thank you for your videos!
@@FlippingPhysics thank you so much for responding so quickly!! I showed him the video and he said that’s exactly what I wanted to do so this is perfect! He is taking physics 1 and wants to go into research so I’m sure he’ll find these videos fun to watch.
There is a basic misconception in this video. The conclusion that the object with a lower moment of inertia will always roll down the ramp faster is incorrect. For example, I can have a very large solid sphere and a very small thin hoop. The sphere has a much larger moment of inertia, but it will still reach the bottom first. The final speed of the object is not determined by the moment of inertia I, but by ratio I/(mr^2).
At no point in this video is it stated that "the object with a lower moment of inertia will always roll down the ramp faster". What is stated is that "The acceleration down the incline depends on acceleration due to gravity, incline angle, and the fraction, X, in front of the mass times radius squared equation for rotational inertia." Another example from the video is "The object with the smallest fraction for the rotational inertia equation, the solid sphere, has the largest percentage amount of translational kinetic energy and therefore is moving the fastest reaches the bottom first." So, I disagree that "There is a basic misconception in this video".
So the time it takes for an object to reach the bottom of the ramp doesn't depend on the moment of inertia of the object itself but on the fraction in front of MR^2? For example, will there be a difference in time taken to reach the bottom of a ramp if two hollow cylinders have different thicknesses?
You are correct that it ultimately is the fraction in front of MR^2 that matters. R is specifically the radius at which it rolls, and not necessarily the overall radius. If the rolling body has two large disks and one inner disk, and rolls down the ramp on the inner disk, it will be the radius of the inner disk that matters. The ratio of moment of inertia to M*g*R^2 will govern how fast it rolls down a ramp without slipping. For hollow cylinders, it depends on how the two different thicknesses compare to the radius. In the limit as the thickness becomes infinitesimal relative to the radius, it ultimately will not matter. If the thickness is significant relative to the radius, you can expect that the thicker cylinder will win. For instance, a 1 mm and a 2 mm thick cylinder, on a 10 cm diameter cylinder will both be close enough to being modeled as thin hollow cylinders that it won't make a noticeable difference. But for a 1 cm and a 2 cm thick cylinder, both with a diameter of 10 cm, it will make a difference. Moment of inertia of a thick cylinder is given by: I = m*R^2*(1 - C + C^2/2) where C is a constant given by C = (R - r)/R, and where R is the outer radius and r is the inner radius. You see as r approaches R, that C approaches 0, and the fraction in front of m*R^2 is 1.
Why can we assume it is rolling without slipping? (I get that it’s an assumed condition but I’m asking is this accurate in the real world?) I assume that unless you’re rolling down ice incline or waxed, it’s very practical that it would roll without slipping.
At slow speeds like this and with common surfaces the objects will roll without slipping. A bowling ball when it is first thrown will roll _with_ slipping until its rotation slows down enough to begin rolling _without_ slipping.
Hello and great videos! I have a question that I can't easily figure out though.. what would happen if you make a sphere that has most of it's mass concentrated in the CENTER rather than the edges? would it roll down even faster than the uniformly distributed one or the same speed? So same total mass but lets say you magically concentrate 80% (or more?) of its mass in a tiny point in the center. Perhaps by putting some extremely dense material in the core of the sphere. How would that sphere behave compared to the other ones? most of these kind of examples talk about uniform sphere vs hollow sphere but not a sphere with a heavy core. Could you give me an explanation? thanks!
I think I’d you understand the derivation of the acceleration down an incline, you will understand the answer to your question. www.flippingphysics.com/rolling-incline.html
The further the particles are from the center (axis of rotation), the faster they go, since V = rω (V is tangential/translational velocity, and ω is the angular velocity). All particles have the same angular velocity, but since the value of 'r' would be different in your case, they'd have a smaller 'V'. Hence, if u concentrate 80% of the particles towards the center, the object would roll down slower, and take a longer time to reach to the bottom. 'Hope this helps 🙂
Nice video, may I ask from where are you getting these problems are you creating them or from a book? if it was a book i would really want to buy/download that book thanks in advance.
Interesting question. The examples in my videos are just like typical examples found in any physics textbook. I have read many of them and at this point am basically just doing the ones I think are most useful.
I love Flipping Physics. My Physics AP teacher told me to drop out of his class when I scored around 65/100 in the first test. He said, "Physics is not for everyone" or take it in college. Then I found Flipping Physics. I worked hard and watched Flipping Physics videos and took notes. I am now scoring on an average above
94 /100. Thank you Flipping Physics.
I like your style.
Thank you sir!
I really like the effort that you put in your videos, they're gems, great work!
Thank you very much!
I love this so much! best teacher ever!
Thanks for the love my friend!
ur amazing !! i discovered this channel yesterday while i was studying mechanics and i've already watched 7 or 8 videos maybe lmao. cant stop, the way u put things it makes them look soooooo much easier. big thanks, luv
Your comment made me smile. Thanks!
I am so sorry that ı was late to find this channel. It is literally awesome. I wish there would be more videos. Quite helpful. Thanks a lot. I could not finish my project without this video.
This helped make moment of inertia actually make sense!! When he said "wait that was too fast" I was like wow facts I am still lost, AND THEN HE EXPLAINED IT PERFECTLY- THIS MAN IS A PHYSICS GOD THANK YOU FOR ALL YOU DO.
Thanks for your lovely comments!!
It really helped me.
Thankyou very much flipping physics🙏🙏
Most welcome 😊
I don't know what I'd do without your videos ❤
Dr. Leonard Hoffstadter. Lovely demonstration.
I'm a drunk physicist, and I'm lovin this 😊
Do not drink and derive.
I love this channel !!!
Thanks for making this awesome videos :D
You are welcome. I am glad you find them awesome!
thanks man. i was having difficulty in understanding this but now its clear
You are welcome!
You're a great teacher. Thank you for such videos
You are welcome!
Thanks ..Sir
...i was very confused with the Moment of inertia Calculation...for Acceleration..
WOW!!! Thank you so much. Your teaching method is very interesting.
This is extremely similar to the demonstration Professor Walter Lewin did for Physics World in July 2014. The biggest different is you provided a far clearer explanation coupled with simple and elegant mathematics that allows people to understand the theory as well as giving people the power to predict how objects will behave in similar experiments. No calculus required 👌
What a lovely comment! High praise. This means a lot to me. 😀
Any chance you could help me out by doing what I ask people to do in this video? bit.ly/2y4tOCA It would be a great way to show your appreciation!
thank you gentlemen.
Another great video. I love your videos as it shows students how to approach and think about the question using the knowledge learnt before solving it.
I am glad you enjoy my teaching style!
I find this explanation using energy is the easiest to understand. The problem I had was trying to understand how this works in terms of forces. It was clear that an object with a higher coefficient for the moment of inertia (the X value in this video) must have a larger force of static friction pointing up the incline compared to one with a lower value of X. But how does having the mass be more concentrated further from the axis of rotation lead to a larger force of static friction? It took me a while to get my head around it to get a more complete picture of what was happening, and it's an explanation I have never seen as this energy explanation is usually the one people go for.
In our assumptions, by definition the the coefficient of static friction is as large as you need it to be, because it is a given that the object rolls without slipping. Concentrating the mass toward the outside, means that the traction has a larger burden to cause a torque about the center of mass, to get the same angular acceleration. No other force causes a torque about the center of mass than the traction.
@@carultch I understand that we can assume that the coefficient of static friction is as large as we like to ensure no slipping, but my point was about what the force of static friction (or traction) is for any given situation. So for a ring and a coin of the same mass, size etc, we know that the force of static friction which provides the torque and thus angular acceleration is larger on the ring than the coin, even if the coefficient for the static friction is the same for both. This coefficient determines the maximum available force of static friction, but it's the coefficient for the moment of inertia that determines the actual force of static friction which occurs for any given situation. The ring will accelerate slower than the coin, even if all other properties (except the MoI coefficient of course) are the same for each. How this happens as a result of a different mass distribution is what I didn't understand and I find most others don't either.
One question .Those 3 objects move down the ramp with a friction.Did friction disregarded in that experiment?
Mr. P is amazing!!!!!!!!! Love from Texas ❤️
Sending love from Michigan. I hope it is warmer there!
*Looking at the question before answer is shown* I think the solid sphere will roll first because of its inertia compared to others
*After watching the video* yah so I was basically right, I just forgot to include the Important pieces in my answer such as the size of the fraction and also the inertia's relations to kinetic and potential energy
That’s what I learned
@@duckymomo7935 yah, it's been a year since I've learned this
Its mind blowing to me that I have lots of lesson I missed when I watch this haha
Sir! U are really a good teacher
Thx
a very interesting result to all of this is that The Final VELOCITY is NOT Dependent on the MASS or RADIUS of any of these Objects.. The Final Velocity is = the Sqrt ( (2gh)/(1+X)) where X is the Factor in front of I= Xmr^2 .... Imagine that??
What a life saver. Cheers mate
How does the final angular velocities of the three objects compare at the bottom of the ramp?
Each week your video lines up perfectly with what we did in class... is that on purpose? It’s amazing
I wish I could claim credit for that. I think it is just blind luck. Soon enough your class will be ahead of the videos I am making. (My pace is actually slower than yours.)
This video was insanely helpful!! Thanks bro subscribed!!!!!😀😀🔥🔥
Glad it helped!
Sir!! You really need to go over some more AP Frqs. It'll help current students a lot!!
Considering Dan Fullerton has already done many AP FRQ solutions th-cam.com/users/FizziksGuyvideos , I don't think it is the best use of my time at this point. Y'all will learn more from specific examples like these. My goal is to make a video for every topic in the AP Physics 1 curriculum.
@@FlippingPhysics Ohh I see! I'm all for it then!
You put so much effort ✔️
Omg this makes so much sense! Thank you so much ^_^
Sincerely, mech eng student
Glad it was helpful!
This boi aced it like a boss😎
#respect+
No words, just wow
thanks
Thank you so much.
Hi! I love your videoes. They are extremly helpful. I have one question. Does the objects in this experement have the same mas? Bc if the hoop has much less mas than the spheres, wont it then have a lower inertia bc there are less masses to sum up, if that makes sense. Bc inertia is the sum of all the masses times radius squared?
I explain the answer to that question in this video: www.flippingphysics.com/rolling-incline.html
Just loveee it!!!
# CONCEPT CLEARED😇
oh man that one is the best technique to learn concept
nice multicamera work
Hi my son is in physics and doing a presentation asking me for hallow and solid balls. I googled and this video came up and it sounds like exactly what he is planning to do. Where can I purchase those spears ? Thank you for your videos!
Those spheres are a racket ball and a field hockey ball. Good luck?
@@FlippingPhysics thank you so much for responding so quickly!! I showed him the video and he said that’s exactly what I wanted to do so this is perfect! He is taking physics 1 and wants to go into research so I’m sure he’ll find these videos fun to watch.
now this is some cool stuff right here, you got a new sub!!!
Hey rolling through your channel for the first time, it's great! :}
I like what you did right there. Nice! (and Thanks!)
Awesome way of teaching..... love it😊😊
Thanks!
There is a basic misconception in this video. The conclusion that the object with a lower moment of inertia will always roll down the ramp faster is incorrect. For example, I can have a very large solid sphere and a very small thin hoop. The sphere has a much larger moment of inertia, but it will still reach the bottom first. The final speed of the object is not determined by the moment of inertia I, but by ratio I/(mr^2).
At no point in this video is it stated that "the object with a lower moment of inertia will always roll down the ramp faster". What is stated is that "The acceleration down the incline depends on acceleration due to gravity, incline angle, and the fraction, X, in front of the mass times radius squared equation for rotational inertia." Another example from the video is "The object with the smallest fraction for the rotational inertia equation, the solid sphere, has the largest percentage amount of translational kinetic energy and therefore is moving the fastest reaches the bottom first." So, I disagree that "There is a basic misconception in this video".
So the time it takes for an object to reach the bottom of the ramp doesn't depend on the moment of inertia of the object itself but on the fraction in front of MR^2? For example, will there be a difference in time taken to reach the bottom of a ramp if two hollow cylinders have different thicknesses?
You are correct that it ultimately is the fraction in front of MR^2 that matters. R is specifically the radius at which it rolls, and not necessarily the overall radius. If the rolling body has two large disks and one inner disk, and rolls down the ramp on the inner disk, it will be the radius of the inner disk that matters. The ratio of moment of inertia to M*g*R^2 will govern how fast it rolls down a ramp without slipping.
For hollow cylinders, it depends on how the two different thicknesses compare to the radius. In the limit as the thickness becomes infinitesimal relative to the radius, it ultimately will not matter. If the thickness is significant relative to the radius, you can expect that the thicker cylinder will win.
For instance, a 1 mm and a 2 mm thick cylinder, on a 10 cm diameter cylinder will both be close enough to being modeled as thin hollow cylinders that it won't make a noticeable difference. But for a 1 cm and a 2 cm thick cylinder, both with a diameter of 10 cm, it will make a difference.
Moment of inertia of a thick cylinder is given by:
I = m*R^2*(1 - C + C^2/2)
where C is a constant given by C = (R - r)/R, and where R is the outer radius and r is the inner radius. You see as r approaches R, that C approaches 0, and the fraction in front of m*R^2 is 1.
@@carultch hey, thanks for the detailed response. I really appreciate it!
Super helpful!
Nice video, how did you do the audio effect please?
thank you!
My question is which of the objects will keep on rolling longer though?
Why can we assume it is rolling without slipping? (I get that it’s an assumed condition but I’m asking is this accurate in the real world?)
I assume that unless you’re rolling down ice incline or waxed, it’s very practical that it would roll without slipping.
At slow speeds like this and with common surfaces the objects will roll without slipping. A bowling ball when it is first thrown will roll _with_ slipping until its rotation slows down enough to begin rolling _without_ slipping.
Thanks, sir.
You are welcome!
this is a great video
I am glad you appreciate it.
Hello and great videos! I have a question that I can't easily figure out though.. what would happen if you make a sphere that has most of it's mass concentrated in the CENTER rather than the edges? would it roll down even faster than the uniformly distributed one or the same speed?
So same total mass but lets say you magically concentrate 80% (or more?) of its mass in a tiny point in the center. Perhaps by putting some extremely dense material in the core of the sphere.
How would that sphere behave compared to the other ones? most of these kind of examples talk about uniform sphere vs hollow sphere but not a sphere with a heavy core.
Could you give me an explanation? thanks!
I think I’d you understand the derivation of the acceleration down an incline, you will understand the answer to your question. www.flippingphysics.com/rolling-incline.html
The further the particles are from the center (axis of rotation), the faster they go, since V = rω (V is tangential/translational velocity, and ω is the angular velocity). All particles have the same angular velocity, but since the value of 'r' would be different in your case, they'd have a smaller 'V'.
Hence, if u concentrate 80% of the particles towards the center, the object would roll down slower, and take a longer time to reach to the bottom.
'Hope this helps 🙂
i wish u would do light/sound wave stuff
amazing
Love from india
Nice video, may I ask from where are you getting these problems are you creating them or from a book? if it was a book i would really want to buy/download that book thanks in advance.
Interesting question. The examples in my videos are just like typical examples found in any physics textbook. I have read many of them and at this point am basically just doing the ones I think are most useful.
Start from 5:23 then see from brgining
0:13 "ball", not "sphere".
I know T = Ia so can a be t/I? a bigger inertia with the same torque would cause a lower angular acceleration right?
Do they have the same torque? If yes, then how so?
And a cube would beat them all, right?
ok so our conclusion is "the further away the actual stuff is from the middle the more inertia it will have
Good
GOAT
great
My dream is also to attend a school in the comfiest clothes and brightest socks I own.
Welcome to Flipping Physics!
Could you do some more AP Physics 1 frq prolems???
Dan Fullerton has already done solutions to every AP Physics 1 FRQ. I do not currently see the need to redo those. th-cam.com/users/FizziksGuyvideos
I say the can
Edit: I was wrong
Noice
this is aids but that ok
Love from india