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A force of 1200N acts along PQ, P(4,5,-2) and Q(-3,1,6)m. calculate its moment about a point A(3,2,0)m
1 Answer
written 3.9 years ago by |
Fpq=1200NΔx=−3−4=−7Δy=1−5=−4Δz=6−(−2)=8∴S=√Δx2+Δy2+Δz2=11.36∴l=ΔxS=−0.62;m=ΔyS=−0.35;n=ΔzS=0.7∴Fx=−744N;Fy=−420N;Fz=840NˉrAP=(4−3)i+(5−2)j+(−2−0)k=i+3j−2kMA=ˉFˉr
MA=|ijk74442084013−2|
MA=i(420(−2)−840×3)−j(744(−2)−840)+k(744×3−420)MA=−3360i+2328j+1812kNm