Question

Determine the moment of each of the three forces about point B, if F1=250N, F2=300N, F3=500N 2m3 m 14 m (MF1)B, (MF2), (MF3)B = [Select] [Select] [ Select] Nm

Answer 1

1. Point 9. 'Determine moment of each of the three forces about B, fi= 250 M, F2 = 300M, Fz=500N · I FES F2 2m 3m . 4 m baf3.

Fifz are inclined so need to break in Honizontal and vertical componuit for the easier. Calculahon - Fico, Fiv = fi cauzo ,f2v = f, Sinbo - f2H=f260360 HEF, Sin 30 4 m - - 2m 3m so we know sum of moment of component is equal to the moment of that force. 1. Moment of folce Fi = 250N about 3. Sign convention "moment of fiv about B, Clockwise dirn => tve Miv=-Fivx Ardist) Anti clockwise diy">)-ve Miv= -Fi Cos 30 X3 (-ve sign because Fiv Poodues ACW Mement about A Miv = +250 COS 30)x3 | Miv=-649.52 N-m) . moment of Fine about B/ MiH = Fil X (Irdist) [fil Prodlucis clw moment about B] MIH= Fisinzo x4 MiH = 250 Sin30 x4. Min = 500 M-m]

force fi is - So, total moment produced by Mi= MHT MV Mia 500+(-649152) | Mi=-149.5 N-m/ Ano this is the moment produced by force fi about B. -ve sign shows Met moment by force fi is of Anticlockwise in Nature. Cill Moment of force-f2 = 300 N about B i "Moment of Far aboutis. M2v = fav x Hr distance) Mar= 0 (because line of action of fzv passing through the point B so, moment will be zero. love sign means F2H Produces] L Acw moment about B sono • Moment of f2H about B M2H == F2H X (fr distance) M2H = -(Acos 60)X 4 M2H = -(300 cas60)x4 M2H = -600 N-m

So, total moment Produced by folle fz is - M2= M2H + Mav M2=-600 to M2=-600 N-m Ans This is the moment produced by force Fa about B. -ve sign Shows llet moment by force fz is of Anticlock wise är nature Ti moment of force 'Fz= 500 N about B 30 Ans The value of moment produced by fz will be zero because, line of action of force F3 passes through the point B. Abel that is why moment become zero.