Eg:
A 760m. distance is measured by applying a pulling force of 90N over the 30m. tape. The tape was made at 50N tensile force. Find the true length of the line if the cross-sectional area of the tape is 0.04cm². Modulus of elasticity = 21х 10⁶ N/cm².
To find:
The true distance between the points. = L =?
Calculation:
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The true length
L = [ Measured length + pull correction.]
L = [ L1 + Cp ]
Now,
The pull correction is calculated by the formula
Cp = [{( Pm - Po ) ÷ A х E } х L1]
Where,
Cp = Correction for pull = ?
Pm = Applied force over tape for pulling = 90N.
Po = Std. pulling force of tape = 50N.
A = Cross-sectional area of tape. = 0.04cm²
E = Modulus of elasticity of tape material = 21х 10⁶ N/cm².
L1 = Measured distance between the points = 760m.
Cp = [{( 90 - 50 ) ÷ 0.04 х 21х 10⁶ } х 760]
= [{ 40 ÷ 0.84 х 10⁶ } х 760]
Cp = 0.0362m.
The true length
L = [ L1 + Cp ]
= [ 760m. + 0.0362m.]
L = 760.0362m.
To understand A to Z of surveying, click here.
Thank you for going through these calculation steps❤. Have a good day 😄.
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