Questions on Moments
The figure AC represents a trap door of width 100 cm which is hinges at A. The weight of the trap door is 30 N and its center of gravity is 45 cm from A. An object is placed on the trap door so that its weight of 40 N acts through B which is 25 cm from A.
Redraw and show on the diagram these two forces and add a force applied vertically at C which just lifts the door. Calculate the magnitude of this force at C.