Answer:
a) The stress in the bar when F is 32,000 is approximately 7,100 psi
b) The load P that can be supported by the bar if the axial stress must not exceed is approximately 110,000 lb
Explanation:
The question topic relates to stresses in structures;
The given parameters of the steel bar are;
The width of the steel bar, W = 4.0 in.
The thickness of the steel bar, t = 1.125 in.
The formula for stress in a bar is given as follows;
![Stress, \sigma = \dfrac{Force, F}{Area, A}](https://tex.z-dn.net/?f=Stress%2C%20%5Csigma%20%3D%20%5Cdfrac%7BForce%2C%20F%7D%7BArea%2C%20A%7D)
The cross sectional area of bar, A = W × t = 4.0 in. × 1.125 in. = 4.5 in.²
∴ The cross sectional area of bar, A = 4.5 in.²
a) The stress in the bar for F = 32,000 lb, is given as follows;
![The \ stress \ in \ the \ bar , \sigma = \dfrac{ F}{A} = \dfrac{32,000 \ lb}{4.5 \ in.^2} = 7,111.\overline 1](https://tex.z-dn.net/?f=The%20%5C%20stress%20%5C%20in%20%5C%20the%20%5C%20bar%20%2C%20%5Csigma%20%3D%20%5Cdfrac%7B%20F%7D%7BA%7D%20%3D%20%5Cdfrac%7B32%2C000%20%5C%20lb%7D%7B4.5%20%5C%20in.%5E2%7D%20%3D%207%2C111.%5Coverline%201)
The stress in the bar when F is 32,000 is σ = 7,111.
psi ≈ 7,100 psi
b) The load P that can be supported by the bar if the axial stress must not exceed, σ = 25,000 psi is given as follows;
![\sigma = \dfrac{ P}{A}](https://tex.z-dn.net/?f=%5Csigma%20%3D%20%5Cdfrac%7B%20P%7D%7BA%7D)
Therefore;
P = σ × A = 25,000 psi × 4.5 in² = 112,500 lb
For the axial stress of 25,000 psi not to be exceeded, the maximum load that can be supported by the bar, P = 112,500 lb ≈ 110,000 lb.