A 160 N force is applies to the handle of a door as shown Th

A 160 N force is applies to the handle of a door as shown. The force vector lies in the plane of the door. Determine the moments of the force about (a) Hinge A and (B) Hinge B.

Solution

component of force in +x-direction is F1= (160 N)*Cos(45)
component of force in +y-direction is F2= (160 N)*Sin(45)

A) The moment arm for force F1 about hinge A, r1 = (1100+400) - 900= 500 mm
   The moment arm for force F2 about hinge A, r2 =  800mm
Therefore, Moment about A = F1*r1 + F2*r2 = 147.08 N-m (out of plane)

B) The moment arm for force F1 about hinge B, r1 = 900 -400= 500 mm
   The moment arm for force F2 about hinge B, r2 =  800mm
Therefore, Moment about B = - F1*r1 + F2*r2 = 33.94 N-m (out of plane)