As you say, "we know that hollow cylinders are slower than solid cylinders when rolled down an inclined plane".

If you have more friction then you will have a much more complicated problem. What was also clear is that for a low-viscosity fluid like water, there wasn't enough friction for the water to "spin up" within the bottle - it all stayed on the bottom half of the bottle throughout the journey, so the water added nothing to the moment of inertia about the bottle's axis.

Speedy Science: How Does Acceleration Affect Distance?, from Scientific American Key concepts When you drop the object, this potential energy is converted into kinetic energy, or the energy of motion. Do you know of any other substance that, in reality, might? Sorry to ruin your day, but this actually has to do with Inertia and distribution of energy. ), A hollow sphere (such as an inflatable ball), A solid sphere (such as a marble) (It does not need to be the same size as the hollow sphere.). So in theory yes, but in reality since $m_{\rm gas} \ll m_{\rm cyl}$ you won't notice a difference. The longer the ramp, the easier it will be to see the results. Gases, as you say, would not produce a noticeable difference. It is a matter of relative density I suppose. It takes more energy to have the hollow cylinder spin (roll) than the solid one. Explain Like I'm Five is the best forum and archive on the internet for layperson-friendly explanations. Now take a hollow cylinder and add a gas (no liquid) inside that rotates with the cylinder (steady state solution) then the gas will add to the mass moment of inertia and it will slow down the cylinder (accelerate less) under the same conditions. Does moment of inertia affect how fast an object will roll down a ramp? Materials, Observations and results By using our site, you acknowledge that you have read and understand our Cookie Policy, Privacy Policy, and our Terms of Service. Think of a lever, it's easier to move something the farther away your side and the it are from the axis. This might come as a surprising or counterintuitive result! Which one will reach the bottom first? Update the question so it's on-topic for Physics Stack Exchange. The mass, partnered with gravity as a force and the lesser friction due to less contact with the surface allows the solid sphere to roll the fastest. (Although they have the same mass, all the hollow cylinder's mass is concentrated around its outer edge so its moment of inertia is higher.). You should find that a solid object will always roll down the ramp faster than a hollow object of the same shape (sphere or cylinder)—regardless of their exact mass or diameter. (Don’t waste food—store it in another container! The solid sphere has the smallest moment of inertia. Each centimeter of vertical drop, as the pieces roll down the ramp, gives them a certain amount of energy, converted from [gravitational] potential energy to kinetic energy (of the two kinds I just described). How has the first atomic clock been calibrated? Physics See silent_b's response. Also, friction between the water and the bottle wasn't enough to make much difference. Let's just consider the solid and hollow cylinders. ), Prop up one end of your ramp on a box or stack of books so it forms about a 10- to 20-degree angle with the floor. Are there proposals for preserving ballot secrecy when a candidate scores 100% in a very small polling station? I have to leave, so I'll leave it to someone else to show the detailed math (it's freshman physics), but here's a short video comparing the two. Speedy Science: How Does Acceleration Affect Distance? Since there is no air to cause resistace, or friction on the feather, they both fall at the same rate hitting the ground at the same time. Introduction How to remove unique strings from a textfile? Why does a hollow ball accelerate faster than a heavy ball? Moment of inertia. Should I speak up for her? Similarly, if two cylinders have the same mass and diameter, but one is hollow (so all its mass is concentrated around the outer edge), the hollow one will have a bigger moment of inertia. Can a wild shaped druid reply to Message?