How Is Downward Displacement Calculated in a Hanging Prismatic Bar?

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SUMMARY

The downward displacement \( d(c) \) of point C in a hanging prismatic bar is calculated using the formula \( d(c) = \frac{W(L^2 - l^2)}{2EA} \). This formula derives from the principles of elasticity and the distribution of weight along the length of the bar. The discussion highlights the relationship between the applied load \( P \), which varies with the vertical position \( y \), and the incremental displacement changes, leading to the integration of the weight distribution. The integration process confirms the presence of the length term \( L \) in the denominator.

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A prismatic bar AB of length L, cross-sectional area A ,modulus of elasticity E ,and weight W hangs vertically under its own weight
a>derive a formula for the downward displacement d(c) of point C which is located at a distance l from the lower end of the bar

The answer is W(L^2-l^2)/(2EA)

how do we get it?

Thanks for any hints or answers!
 
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Well, so delta = PL/EASo P varies along the y direction...P = W*y/L, right?

and if we're doing incremental displacement changes, the L is your dy

d delta = integral W*y/LEA * dx

so you integrate from your l to L. Shouldn't your answer also have an L term in the denominator?
 

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