Person is lifting a 250 N dumbbell. The weight is 30 cm from the pivot point of the elbow. What force must be exerted five from the elbow to lift the weight? Assume everything is perpendicular.
For dynamic equilibrium, the sum of moments about the elbow is zero. Take moments about the elbow. (5 cm)*(F N) - (30 cm)*(250 N) = 0 F = (30*250)/5 = 1500 N
