Evlich

This is a pretty simple project. We get sand concrete mix, coat hangers, and we can make the form from cargboard and ducttape.

Here is the thing, the total thing can only be 2 in from base of the lowest part to the top of the highest part. If I do an arch, and that would probably be difficutl to make a form for, I would only be able to slope it a little and it would end up being very thin? It seems like that would make a difference, but would the arce itself be enough to overcome the lack of actual concrete, does that even affect it? Thanks a lot for your advice. ~evlich

Hello, I am working on a project to design a concrete beam that is 2in x 2in x 12in that will be able to hold the most weight. I have been searching the web for a while for any similar projects and all that I can't seem to find anything relatively simple (I am a high school student and I am doing this for a design course, not really an in depth physics course). I am just looking to have some general place to start my design with. Thanks a lot, any help is greatly appreciated. ~evlich

Ok, that is the part that I understand, what I don't understand is will I have to model the torques as rotating around the x, y and z or can you do it with just an xy angle and an xz angle? I have the force as a 3D vector and the distance from the rotation as a 3D vector. I take the cross product and from that I get something, but I am not quite sure what I get. I already have the motion working perfectly in 3D, can you explain how I can get from on instance, to the next. For instance, I know where everything is, how fast it is moving, how fast it is rotating and what it is rotating around, how do I use that to get the torque as a 3D vector (I was only shown the way to get it as a torque in the xy plane). Thanks a lot.

Hello, I am working on a project modeling the solar system and I am having quite a bit of trouble with this rotation thing. If I have a moon that could potentially rotate in three dimentions, how can I calculate the torques on the object. I found an example of how to do it for 2 dimensions that is really good, but I don't understand how I should model it for 3 dimensions. Do I need to keep track of its rotation around the x y and z axis or just its rotation in the xy plane and in the xz plane? And how would I go about computing the torques. The example shows how to do it easily with cross products and stuff, and I kinda understand that, but I can't seem to picture it in 3 dimensions. Thanks a lot for your help.

Hello, I have been searching for forever to try and figure out this Kepler's law stuff. I know that planets don't follow circular paths around the sun, but rather their paths are eliptical, the same with moons and other things. My question is "Why?" The diagram that I looked at showed that one of the foci would be the sun (for a planet orbiting the sun) and the other would be some blank place in space, so what I want to know is why is that blank place in space so important that planets are attrated to it. The same goes for moons orbiting the planets. Any explainations or links on the topic would be greatly appreciated. Thanks a lot for all of your help.