Question

A level was set up at point 'C' at a distance of 100m from 'A' and 1000 m from 'B'. The staff reading on the staff kept at A was 0.445 m and that on the staff held at B was 2.845m. The true difference in elevations (in m, correct upto three decimal places) of A and B is _________

• A. 2.3334

Answer 1

The correct option is A 2.3334
Correction at A $=-0.0673d^2=-0.0673\times {0.1}^2=-6.73\times {10}^{-4}m$

Corrected staff reading at A = staff reading at 'A' + Correction at 'A'

$=(0.445-6.73\times {10}^{-4}m)$

= 0.4443 m

Correction at B = -0.0673 × 1${}^2$ = -0.0673 m

Corrected staff reading at 'B' = (2.845 - 0.0673)m
= 2.7777 m

Difference in elevations = (2.7777 - 0.4443)m
= 2.3334 m