The same couple moment of 80.0 lb⋅ft is required to open the hatch door, independent of where the couple's forces are applied. If the forces are applied at points C and D, what force magnitude F is required to open the hatch door?

force magnitude F  required to open the hatch door is 4.44 lb

Explanation:

given data

couple moment = 80.0 lb⋅ft

solution

we consider here radius r

r = 9 ft

so here moment is express as

moment = F × (2 × r )   ........................1

put here value

80 = F × (2 × 9  )

80 = F × 18

F =  

F = 4.44 lb

resonant frequency