TC Qn: 176 7 A rigid cross-shaped structure having four arms PO, SO, QO and RO, each 1.00 m long, is pivoted at O. Forces act on the ends of the arms and on the midpoints of the arms as shown. 9702/12/O/N/16 R 70N 30 N 20 N 50 N P I O Q 1 50 N 30 NA 20 N A 70 N D S What is the magnitude of the resultant moment on the structure about O? A 45 Nm B 90 Nm C 120Nm 190 Nm​