Section $2$: Stress Analysis $(20$ points$)$

This is the same four bar used in your previous homework. We put a few

sensors in our joints and measured the following values:

$Fcx=-0\mathrm{.}57N$

$Fcy=2\mathrm{.}22N$

Fox$=10\mathrm{.}57N$

Foy$=-2\mathrm{.}22N$

$T=688\mathrm{.}09N**mm$

A curious engineer discovered that the tangent of the angle theta$4$ had the

same value of Fcy divided by Fcx$.$

a$.$ Thinking about direction of forces, and all the possible kinds of stresses

that a system can be subjected to$,$ what are the stresses present at the

link BC$?$

b$.$ Could I replace the link $BC$ with a fishing line made of nylon, with a

circular section area of $1m{m}^2?$ Calculate the stress $$ we would

observe in this situation? $($Attention to units: Pa is given by $\frac{N}{m},$ while

$1\frac{N}{m}m$ would automatically be $1$ kPa $)$

c$.$ If I were to tell you that the Yield Strength of our material was $100$ MPa $,$ and considering a Safety Factor

of $2,$ what is the smallest diameter possible? $($Hint: The cross$-$section of this wire is circular, and the

values that you will find will be very small$)$