Forces — practice question

A beam of negligible weight is in equilibrium on a pivot, as illustrated. Forces P, Q and R are acting on the beam. Which equation is correct?

• A$(P \times c) + (Q \times b) = (R \times a)$
• B$(P \times c) - (Q \times b) = (R \times a)$
• C$(P \times d) + (Q \times b) = (R \times a)$
• D$(P \times d) - (Q \times b) = (R \times a)$