Engineering
posted by Aaron .
Calculate the moment about a point (5; 4; 3) ft. caused by the forces
P = 3^i  2^j  4^k lb. and Q = 5^i + 7^j  2^k lb. acting at the points
(7; 2; 2) ft. and (3; 2; 5) ft., respectively.
What I did was this;
vector r1= (7,2,2)  (5,4,3) = 2i2j5k
vector r2= (3,2,5)  (5,4,3) = 8i6j+2k
Vector M1= (2i2j5k) X P = 7i7j+2k
Magnitude= 7.55 ftlbs
Vector M2= (8i6j+2k) X Q = 2i6j+85k
Magnitude= 86.23 ftlbs
Moment about the given point = (7.55) + (86.23) = 93.78 ftlbs
I'm unsure if this is right
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