An experimental balance bar of length 120 cm is suspended from a ceiling by a vertical support wire connected at pivot point PPP, located at the 30 cm mark.
Two test weights, X X\,X and YYY, are suspended from the bar as shown in the diagram:
- Weight XXX: 4.2 N, suspended at the 55 cm mark.
- Weight YYY: 2.6 N, suspended at the 90 cm mark.
Show that the total moment of X X\,X and Y Y\,Y about pivot P P\,P is 2.61 N m.