Posted by Aaron on Sunday, February 12, 2012 at 3:30am.
A force F = 7^i + 6^j  5^k lb. acts at the origin. Find the magnitude and
direction cosines of the moment of this force about point A (4; 5; 6) ft
So in this case wouldn't
vector r= 4i +5j +6k
and
vector F = 7i + 6j  5k lb?
and r X F = 61i +22j 59k = MA
[MA]= 87.67 ftlbs
cosα = 61/87.67 => α=134°
cosß= 22/87.67 => ß=75.5°
cosγ= 59/87.67 => γ=132.3°
Not sure exactly where I went wrong because those angles don't make any sense.

Engineering/Physics  drwls, Sunday, February 12, 2012 at 5:46am
If the force acts at the origin, the lever arm r about point A is the opposite vector,
r = 4i 5j 6k

Engineering/Physics  Aaron, Sunday, February 12, 2012 at 2:21pm
Ah, I knew there must be something off about my answer.
Thank you so much!!!
Answer This Question
Related Questions
 Engineering  A force of 26 lb. acts through a point (4; 5; 7) ft. and is ...
 physics  A force 1 of magnitude 5.40 units acts at the origin in a direction 45...
 Physics/ Engineering  Calculate the moment about a point (5; 4; 3) ft. caused ...
 Physics  A force F1 of magnitude 6.90 units acts on an object at the origin in ...
 Physics  A force 1 of magnitude 7.20 units acts on an object at the origin in a...
 Physics  A force F 1 of magnitude 5.90 units acts on an object at the origin in...
 Engineering  Calculate the moment about a point (5; 4; 3) ft. caused by the ...
 Engineering  Calculate the moment about a point (5; 4; 3) ft. caused by the ...
 physics  A force Farrowbold1 of magnitude 5.00 units acts on an object at the ...
 physics  A force in the +y direction applied at the point x=2.3m,y=1.4m gives ...
More Related Questions