and the downward force vec$(R)$ exerted by the humerus on the forearm, acting at the joint. Neglect the weight of the forearm.

Figure $8\mathrm{.}11($a$)$ A weight held with the forearm horizontal. $($b$)$ The mechanical model for the system.

Strategy The forces acting on the forearm are equivalent to those acting on a bar of length $0\mathrm{.}359m,$ as show in Figure $8\mathrm{.}11$b$.$ Choose the usual $x-$ and $y-$coordinates as shown and the axis $O$ on the left end. $($This completes Steps $1$ and $2.)$ Use the conditions of equilibrium to generate equations for the unknowns, and solv

Solution

Apply the second condition for equilibrium $($step $3).$

${}_i={}_R+{}_F+{}_{BB}=0$

$R(0)+F(0\mathrm{.}0308m)-(49\mathrm{.}3N)(0\mathrm{.}359m)=0$

$F=,N$

$F=,lb$

Your response differs significantly from the correct answer. Rework your solution from the beginning anc check each step carefully.

Apply the first condition for equilibrium $($step $4).$

$F_y=F+R-49\mathrm{.}3N=0$

$R=F-49\mathrm{.}3N=575N-49\mathrm{.}3N$

$R=,xN$

Your response differs significantly from the correct answer. Rework your solution from the beginning an check each step carefully.

$R=$

Ib

Your response differs from the correct answer by more than $10\%.$ Double check your calculations.