A timber post $150$ mm square has two steel plates $150$ mm x $6$ mm bolted to it on opposite

sides along the entire length of the post. Calculate the stresses in the timber and steel due to

a vertical axial load of $350$ kN$.$ If the post is $3$ m high calculate the amount of shortening

under the load. E for steel is $205$ kN$/$mm$2$

and E for timber $8200$ N$/$mm$2$

$.$