Final answer:
The cross-sectional area required for link AB with an ultimate normal stress of 65 ksi and a factor of safety of 3.20 can be determined using the formula σ = P / A, where σ is the required stress of 20.3125 ksi. However, without knowing the actual load P, the exact cross-sectional area cannot be calculated.
Step-by-step explanation:
To determine the cross-sectional area of link AB for which the factor of safety will be 3.20 when the material's ultimate normal stress is 65 ksi, we use the following formula:
Required stress = Ultimate stress / Factor of safety
Thus, the required stress that the steel can withstand while ensuring a factor of safety of 3.20 is:
Required stress = 65 ksi / 3.20
Required stress = 20.3125 ksi
Now, to find the cross-sectional area (A), if the load (P) the link can carry at this stress is known, we use the stress (σ) formula:
σ = P / A
And rearrange it to solve for A:
A = P / σ
If P is unknown, additional information regarding the load the link needs to support is necessary to calculate the specific cross-sectional area. Without this information, one cannot provide a numerical value for A.