- #1
jamesbob
- 63
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Three forces with magnitudes [tex]F_a, F_b, F_c [/tex] act on a point mass, pulling in unit directions a, b, c, respectively. Thr forces are in 'equilibrium' which means that
By taking the cross product with a, show that
and find two similar equations (involving [tex]F_a[/tex] and [tex]F_c[/tex], and [tex]F_a[/tex] and [tex]F_b[/tex], respectively).
My Work
I'm quite stuck here, i don't think i understand fully. The only mere working i can muster is:
[tex] a \times (a \times b) = (a.b)a - (a.a)c [/tex]
[tex] a \times (c \times a) = (a.a)c - (a.c)a [/tex]
Can anyone help me out?:uhh:
[tex]F_aa + F_bb + F_cc = 0[/tex]
By taking the cross product with a, show that
[tex]F_b(a \times b) = F_c(c \times a)[/tex]
and find two similar equations (involving [tex]F_a[/tex] and [tex]F_c[/tex], and [tex]F_a[/tex] and [tex]F_b[/tex], respectively).
My Work
I'm quite stuck here, i don't think i understand fully. The only mere working i can muster is:
[tex] a \times (a \times b) = (a.b)a - (a.a)c [/tex]
[tex] a \times (c \times a) = (a.a)c - (a.c)a [/tex]
Can anyone help me out?:uhh:
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