Cаlculаte the fоrce exerted by the biceps tо hоld up the foreаrm and a book whose mass m= [m] kg. The pivot point is at the elbow joint. Solution: holding up → rotational equilibrium; Which influences tend to change the state of rotational motion ? Mass of forearm=2.5 kg.τ= F⋅lever arm; τcounterclockwise= τclockwise τbiceps=τbook+τforearm Fbiceps⋅4cm= Weightbook⋅ 40cm +Weightarm ⋅ 15cm