$1\mathrm{.}9-1$

$1\mathrm{.}9-1$ A bar of solid circular cross section is loaded in tension by forces $P($see figure$).$ The bar has a length $L=380mm$ and diameter $d=6mm.$ The material is a magnesium alloy having a modulus of elasticity $E=42\mathrm{.}7$GPa. The allowable stress in tension is ${}_{\text{a}\text{l}\text{l}\text{o}\text{w}}=89\mathrm{.}6$MPa, and the elongation of the bar must not exceed $0\mathrm{.}8mm.$

What is the allowable value of the forces $P?$

Pl$.$