Question

5. A transmission tower is held by three guy wires attached to pin at A and anchored by bolts at B, C, and D. The magnitude of the tension force Fab in wire AB is 840 lb. a) Determine the force vector Fab and its moment with respect to origin O. b) What is the moment of Fab about the axis passing through points C and D? A 30 m D 6 m 7.5 m O 22.2 m 6 m 18 m 5.4 m 1 Fig.5

Answer 1

que ! om 3om 7 7.5 ta 22.2m 70,0,0) +3 Bo 18 m Sound om I FAB fuo lb Co-ordinate of 10,0,0) 10,30,0) 8 = (-6, 0,715) A C = ( 18,0, 5.4) D = (-6,0, -22.2) distance AB = (-670)2+(30-0)2+(705-092 31.5m BÂ= JA - OB 309 - (-6ť +7.56) Gê +357 -7.5 unit veita Csscanned with CamScanner (V) 61+30f-7.5k 31.5

folce vector FAG - fagod Bit (si +301-7.56) 31.5 (b) Moment of FAB about the axis passing through cdo CD ーで eius =(-61-2126)-118i+5.4%) -24 i-a76 -24 -27.6 unit vector 36.57 force is passing through a point, and point on on the axis so- huoment alm: TOA = Ă - 3 = (30) )--61 – 22-2ķ) Bolo Gît30)+2202 $40 (61+309–76560) force Vector - 31.5 .-27.6 -24 36.57 36.5 771912-3486.3 Moment of facce 30 22.2 6 160.02 4232.8 db.m cscanned with CamScanner 200 800.1