$)$ To correct a birth defect, the tibia is straightened using

three wires that are attached through holes in the bone

and then to an external brace that is worn by the patient.

$**$Consider the point of application as the point where the

wire is secured to the bone $($not the frame$).$

a$)$ Determine the frontal plane torque $($moment$)$ of

each wire about the centre of the knee joint $($A$),$

AND calculate the frontal plane net torque

$($moment$)$ about the knee joint $($A$)$ from the wires

$($state the sum of all the torques$).$

a $=0\mathrm{.}06$m $2=-25$o $(335$o FRH$)$

b $=0\mathrm{.}13$m F$1=540$ N

c $=0\mathrm{.}08$m F$2=1140$ N

d $=0\mathrm{.}05$m F$3=860$ N

e $=0\mathrm{.}04$m $1=35$o $(35$o FRH$)$

f $=0\mathrm{.}06$m

g $=0\mathrm{.}02$m

$($a$,$ b$,$ c$,$ d are vertical distances from bottom to top$)$

$($e$,$ f$,$ g are horizontal distances from top to bottom$)$