For the figure shown: a) Determine angle between cables AB and AC. b) Determine
ID: 1861013 • Letter: F
Question
For the figure shown:
a) Determine angle between cables AB and AC.
b) Determine the projection of force FAB on the strut OA.
Express result as a Cartesian vector.
c) Determine the magnitude of the vector perpendicular
to the projection of FAC on the strut OA.
Express this result as a Cartesian vector
I ONLY NEED PART C SO DON'T BOTHER WITH A OR B
Explanation / Answer
so we want to find (FAB * AO) AO
so AO point in the direction -6ft j - 2 ft z
now we have to normalize
so divide by sqrt(6^2 + 2^2) = sqrt (36+4)=sqrt(40)=2*sqrt(10)
so AO= 1/sqrt(10) [ -3 j - 1 z]
now FAB points in the AB direction
AB points -3i -6j +2k
normalization is sqrt(3^2 +6^2 + 2^2) = sqrt( 9+36+4)=sqrt(49)=7
so FAB=70lb* 1/7 (-3i -6j +2k)
FAB= (-30i -60j + 20k) lb
so FAB*AO=(-30i -60j + 20k)*1/sqrt(10)[ -3 j - 1 z]=1/sqrt(10)[-60*-3+20*-1]=50.596
so (FAB*AO)(AO)= 1/sqrt(10) *(-3*50.596 j - 50.596 z)= -48 j -16 k