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Homework Statement
The thick arrows represent forces exerrted upon the mast
Let ## \vec{r_2} = ~~the~~ longer~force~ vector~~##
## \vec{r_1} = ~the ~shorter ~force ~ vector##
correspondinly ## \vec{R_2} = cable ~~2##
## \vec{R_1} = cable~~1 ##
r_1 is in the same direction as R_1
r_2 is in the same direction as R_2
(I could not find the correct latex symbol for this, I want two vertical arrows side-by-side both facing upwards)
The thinner lines parallel to the forces which have endpoints in the xy- plane, those thin lines are the cables which are attached to the ground (xy- plane ostensibly) The cables are attached high up into the top of the mast. There's two cables and two forces in the picture currently.
a) calculate the two forces in the picture and give their coordinate form (using unit vectors)
b) calculate the sum of the two forces
c) a third cable is attached as follows. The tension is 800 N. Its endpoint will be (x, y). Define the force exterted upon the mast from this cable. (using unit vectors)
d) into which point in the xy plane, must the third cable be attached such that the resultant force from the three cable forces will be in the same direction as the mast ( the last part was a little bit unclear, but using common sense it would seem the resultant force needs to point down into the ground, and be parallel to the mast ?)The c) part was a little bit unclear to me what is being asked exactly.
Homework Equations
The Attempt at a Solution
a)## \vec{r_2} = 272.91 \hat{i} + 682.22 \hat{j} - 818.62 \hat{k} ##
## \vec{r_1} = - 471.5 \hat{j} - 707.24 \hat{k} ##
b) ## \vec{F_{sum}} = \vec{r_1}+ \vec{r_2} = 272.91 \hat{i} + 210.725 \hat{j} - 1525.86 \hat{k}##c) I was a little bit unconviced of finding a definite solution for the endpoint of the third cable on the xy plane.
c1) It seems as though infinite number of points exist as solutions ? The length of the third cable is ostensible finite length, but it is unknown length also.
c2) We only know the force exerted by the third cable upon the mast. Not the length of the third cable.
c3) If the cable were of fixed length such that the third cable is called C
c4) C is attached to the top of the mast, and C is a taut line, somewhat analogous to a stick. C will draw out a circle in the xy plane. All those points in the circumference of the circle are correct solutions for point (x,y)
c5) the radius of the circle in xy plane will be fixed value, but we don't know the radius because we don't know the length of the cable C.