Question

. A base line was measured to be 150 m long with a tape at a field temperature of 27°C, the applied pull being 14 kg. The tape was standardised at a temperature of 15°C with a pull of 8 kg. If the designated length of the tape is 20 m, weight of 1 cm of tape = 7.86 g, total weight of tape = 0.8 kg, E = 2.109 x 106 kg/cm² and coefficient of expansion of tape per degree Celsius 11.2 x 10°, find the true length of the line. (Ans. 150.0081 m)

Answer 1

Temperature correction per tape length=

$( Ct ) = α(Tm−T0)L$

$=3.5×10−6(34–25)×30$

$=9.45 × 10^{-4} (+VE)$

To find pull correction per tape length(Pull correction per tape length)

$= \frac{p_{m-P_0 } L}{AE}=\frac{(18-10)30}{(0.025 × 2.1× 10^6 ) } = 150.008 \space m$