Recent content by dttah

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    Rigid Body Rotation: Find Vel & Action on Axis in Eq. Pos.

    Got it, so it'd be like: Let M be the mass of the disk m be the mass of the point For the disk: Mg(radius/2) For the mass point: mg(radius+radius/2)
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    Rigid Body Rotation: Find Vel & Action on Axis in Eq. Pos.

    Alright, thanks for the suggestion, I'll try to stick to that from now on.Here is the numerical correction, I = 1.28 + 0.64 = 1.92. Now uhm. The center of mass of the disk is the center of the disk, which is rotating alone point A. Radius would be OP/2. It'd move pi/2 radians, shoudln't it...
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    Rigid Body Rotation: Find Vel & Action on Axis in Eq. Pos.

    Alright, so the center of mass would be the center of the disk itself. So it'd be.. 1/2 MR^2 + MD^2. Where the distance here would be OP/2. So 1/2 (4kg) * 0.8m + 4kg*0.4m = 3,2. Now I found the moment of inertia (if I did it right, lol) of the disk rotating alone point A. The moment that...
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    Rigid Body Rotation: Find Vel & Action on Axis in Eq. Pos.

    I am sorry if I am a little slow but as I said I am just starting out with these. The disk isn't rotation around its center of mass (the center), so we have to apply the integral of r^2dm in order to find out the moment of inertia? Or maybe I could apply the parallel axis theorem?
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    Rigid Body Rotation: Find Vel & Action on Axis in Eq. Pos.

    Holy, that's kind of unexpected, I mean I don't see any wire nor talking about gravity, so yeah, the idea didn't even pass by my mind. I don't get why you say that "This is all about rotation about a point other than the center" Why's that?
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    Rigid Body Rotation: Find Vel & Action on Axis in Eq. Pos.

    Homework Statement A system is made of the following things: A homogeneous disk of mass m = 4kg. Having radius r = 80cm's. A point P (m = 2kg) free to rotate around a horizontal axis which is perpendicular to the disk in point A. AO = OP/2 If the system starts from rest and AP forms a...
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    Inclined plane with spring underneath.

    I don't think I follow.
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    Inclined plane with spring underneath.

    the spring would be perpendicular to the inclined plane, something like this (check attachment). So, a question, when we have an inclined plane, and we want to find the potential energy. mgh h is always the height from the ground or it should be relative to the inclination of the plane?
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    Inclined plane with spring underneath.

    It means that when it is not compressed, the spring has a length of 30cm's. Then when the block pushes it, it's compressed of a maximum of 12 cm's. Now I would like to know what I must plug into x.
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    Inclined plane with spring underneath.

    Homework Statement A body of mass m = 2.5kg is on a frictionless inclined plane (by 40°). At an height of h = 1.6m. On the bottom of the plane there's a spring, which at rest has an extension of 30cm. If the spring is compressed maximum of 12cm, what's the "k" of the spring? Homework...
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    Collision with an object after circular motion.

    woops, my bad :)... okay got it! Thanks a lot. That's appreciated.
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    Collision with an object after circular motion.

    Ok so: 1/3ML^2 => 1/3 0,5kg * (1.50) I = 0,25. mgh = 1/2Iw^2 w = square root of... (2mgh)/I So w = 5,42 rad/sec Velocity = radius * w => velocity = 1,50 * 5.42 = 8.13m/s And then the other stuff is just an elastic collision which I should know how to handle. Just one...
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    Collision with an object after circular motion.

    It'd be 1/2Iw^2 where I = momentum of inertia So it'd be: 1/3ML^2 => 1/3 0,5kg * (0.75) (I am not sure, but this should be it?) Then I can do the following: mgh = 1/2Iw^2 Where I have I, m and g. I can assume that h = 0,75 because it'd be the radius, and so I could find the angular velocity?
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    Collision with an object after circular motion.

    Since there is no talking about density I can assume the center of mass is just L/2 so: x = 0,75. Right? Now I understand that I have to do something with energy, so like: mgh = 1/2mv^2 But I have to decompose the motion in x and y. I am not sure if this is correct but this is my...
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    Collision with an object after circular motion.

    Homework Statement "A bar line AB has a length of 1,5m and a mass of 0,5kg. It is stuck in the point B in a horizontal fixed hub, and it can oscillate freely with no friction in the verical plane. at time t=0, the bar line, which was still (not moving, inertia), is set free to rotate. When it...
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