Quote:
Originally Posted by Kevin Sevcik
Joe,
Do you know what form the expected answer should take? If it's simply looking for the ratio of the magnitude of OA to the projection, then that's pretty easy and Jack's advice applies.
If they're expecting you to calculate an actual load on OA, then that's a little trickier. In that case it turns into a system of 3 equations. On that track, the idea is that the loads on OA, OB, and OC add up to your load, but in the opposite direction. So FOA + FOB + FOC = (0,0,1000). The trick there is, again, to nomalize (turn into a unit vector) OA, OB, OC. Then you can multiply those unit vectors by a magnitude and end up with a system of 3 equations.
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All I know is that they want the magnitude of the projection of OA onto the positive z axis... I dont think they want the load. So I am assuming that they want how much OA is pulling up on the Z axis. In other words, what part does it have in the system of 3 cables since it isnt a single cable pulling up on the z axis.
The exact question from the book is in quotes in the original post... admittingly it is pretty inspecific.