Final answer:
The maximum allowable force in a 20 mm diameter bar without exceeding an average normal stress of 150 MPa can be calculated by multiplying the stress limit by the cross-sectional area of the bar.
Step-by-step explanation:
When discussing the average normal stress in a material such as steel or brass, we are dealing with an Engineering topic, specifically within the mechanics of materials. The average normal stress is defined as the internal force divided by the cross-sectional area over which the force acts.
For a cylindrical rod or bar, the area, A, is given by the formula A= πr², where r is the radius of the rod. To ensure that the average normal stress does not exceed a specified limit, you would have to calculate the maximum allowable force using the stress limit and the cross-sectional area of the bar.
For a bar with a diameter of 20 mm (radius 10 mm or 0.01 m), the area A is π(0.01 m)².
If the stress must not exceed 150 MPa (150×10⁶ N/m²), the maximum allowable force F can be found by multiplying the stress by the area, F= stress × area.
Therefore, F= 150×10⁶ N/m² × π(0.01 m)².
By performing this calculation, we can determine the maximum force each bar can support without exceeding the given stress limit.