Question

Z F B Find the moment of the force, F 1916 shown above Figure with respect to the origin and with respect to point C when A(2, - 4, 10), B(7,2, 4), and CC - 6,6,6) ft. Mo i + j+ Mc = i + jt k) lb. ft k) lb. ft

Answer 1

Criven Data I FI = 1906 A (2,-4, 10) A B (7,2, 4) C (-6, 616) ft Solution Find moment about Origin (o, o, ol First we need to find fora direction Force lie in the direction AB line vector ALB BA= (2-+ -4-2) 9 + (1-4)%

BA = -5 6 § 6 Now finding foru vector E = magnitude of Flv unit vectored Unit vector BA = - 5 7 6 9 +6 ✓ 3² +6² +6² F = (19) [-sî - 6h tok) (9.84) TIL (1.929) [-sâ -69 +6R Now this vector (Fl floal & cross products gives ay moment about origin Mo (OAX F OA (2-0 Iņ +1-4-09 + (10-0) Å A = 2 î -4 9 tlo k CA Mo = (2ņ ug tok) x (1929) [-s^-6 h + 6k]

ÑO = (1:829) ED Ã - 2 -4 10 -5 6 Mo = (4929) (-24+6)9 -9 (1245) + 42*=2) Mo = (4.929) [ 36 - 62 - 227] [CP) 61.7288 ] lb-ft 69.49 û - 119.598 Ans Moment a bow origin Now similar thing would be done to find moment about a AC = (2+6 ↑ +1-4-6) § 40-6) & AC = 8î lo ý tq Me or (he) x (4:02) [199=13*** )* (-58 -43 +68)]

Mc = (1-923) (-36) + (-6) - R (98)] -69.44 - . 131-172 9 - 189.042 I felbft AN