Determine the stretch in each of the two springs required to hold the 20-kg
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- čas přidán 9. 09. 2024
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Determine the stretch in each of the two springs
required to hold the 20-kg crate in the equilibrium position
shown. Each spring has an unstretched length of 2 m and a
stiffness of k = 300 N/m.
You solved all my assignments! Thank you!
How do you determine that uA and uB are 0i -1j +0k and -1i +0j+ 0k respectively?
If I try to find the coordinates of point A, I don’t feel secure in saying that I know point A is -1 along the y-axis because I don’t know HOW far A is from the origin along the y-axis. I only know that the unstretched length of the Spring is 2 m. Same for the location of point B: I only know that the unstretched length of the Spring is 2 m. Wouldn’t that put both point A and point B at least 2 m away from the origin, not the 1 you are using? Why do you use 1?
KidsandKarma I think it is because the unit vector is the length over the magnitude of that length. If A were 2m away for example your unit vector would be (-2)/sqrt((-2)^2). This equals -2/-2 which equals -1 (as A is going to the left). Because A has no x or z component this must be true (otherwise the values in your square root would be greater because you'd add those components).
I finally figured out what the problem was. I couldn't see that the lines attaching the springs to the origin were actually part of the springs themselves. Those lines are written thicker, but this can't be seen in the digital version. Looking closely at the printed version I was able to see it.
Oh I see what you are saying. Yeah when I do these problems I consider the spring to be the entire length even though it doesn't look like it. It's weird.
Its unknown but since it's along one axis it's unit vector can be positive 1 or negative 1
How do you know A and B is already in unit vector?
How come you didn't use the 2 m for the unstretched length?
dont need it to find the stretch, if they wanted you to find the deformed length of the spring after the stretch you would use it.
Dude your awesome thanks a ton
Thanks so much brother
does anybody know where the little c's are coming from that he is attaching to the unit vector for c????
what textbook is this question from?
THANK YOU!
doing good job .god bless u
what about the 2m from the question?
he skipped a step. he already he divided the vector coordinates of rA and rB by the the magnitudes, which are both 2, and that gives you uA and uB.
Super