Hey, guys. So here's another classic rotation question that we're going to use conservation of energy to solve, and it's a yo-yo question. Right? So, we have a simple 100-gram yo-yo that we're going to release from rest. Now, "simple" just means that you're going to be able to make some assumptions to simplify the yo-yo. Yo-yos are actually more complicated than how we're going to solve them. But here we're going to simplify. That's what "simple" means. It just means, you know, go nuts with simplifications. Alright. So, mass equals 0.1 kilograms. It starts from rest, v_initial equals 0. It falls and rolls. Yo-yos do that. Right? So they're falling and rolling on the way down, unwinding the light string around its cylindrical shaft. So as it falls, it unwinds a light string. The yo-yo has a string around it. The "light" string means the mass of the string is negligible around its cylindrical shaft, and that's because a yo-yo has a yo-yo has a thing in the middle. The cable, the string is here, but then the yo-yo usually has sort of an outer casing like that. Right? The idea is that what matters is this inner radius, not the outer radius. The outer radius just covers the outside. So effectively, we're going to just worry about this and say that a yo-yo looks like this. Okay. Let's actually put the little string here. Now if the string is here and you release a yo-yo, it's going to fall and it's going to roll like this. So if the string is on this side, it's going to go like this. This is the velocity of the center of mass, and it's also going to spin with the omega. Okay. So, the radius of the inner, which is what matters, is 2 centimeters. So 0.02 meters. It says if the yo-yo can be modeled after a solid disc, in other words, treat this thing here as a solid disc, right, which is what we're going to do. In other words, I will be half m r squared because that's the I for a solid disc. I want to know what is its line
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