How do I calculate the factor of safety for a prismatic bar under tension?

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SUMMARY

The factor of safety (F.S.) for a prismatic bar under tension is calculated using the formula F.S. = allowable stress / actual stress. In this case, with a load of 37 N and a cross-sectional area of 5.7 cm² (0.00057 m²), the actual stress is calculated as 37 N / 0.00057 m², resulting in an actual stress of approximately 64,912.28 Pa or 64.91 kPa. Given the allowable stress of 100 kPa, the factor of safety is determined to be 1.541, confirming that the member can safely withstand the applied load.

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  • Knowledge of the concept of factor of safety
  • Basic principles of mechanics of materials
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Kazaam
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There is a question on my home work that I just don't understand how they got the answer they did.

The first question is:
In a prismatic bar, the load applied on both ends is 37 N causing the member to be in tension. If the cross section area of the member is 5.7 cm2 and the allowable stress is 100 kPa. What is the factor of safety for the system?

I got .1.298 kpa, the answer is supposed to be 1.541 kpa, how does (37N/.057)/100 kpa= 1.541 Kpa, what am I missing here?
 
Last edited:
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Kazaam said:
There is a question on my home work that I just don't understand how they got the answer they did.

The first question is:
In a prismatic bar, the load applied on both ends is 37 N causing the member to be in tension. If the cross section area of the member is 5.7 cm2 and the allowable stress is 100 kPa. What is the factor of safety for the system?

I got .1.298 kpa, the answer is supposed to be 1.541 kpa, how does (37N/.057)/100 kpa= 1.541 Kpa, what am I missing here?
5.7 cm^2 = 0.00057 m^2. And then you incorrectly have written that F.S. = actual stress/allowable stress...what should that equation be??. And what are the units of the safety factor?
 
Last edited:

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