Correct Answer - Option 2 : 7.5 cm
Explanation
Given,
Length = 60 m
Gradient = 1 in 20
Gradient = h/L
\(\tan {\rm{\theta }} = \frac{1}{{20}} = \frac{h}{{60}}\)
⇒ h = 3 m
We know slope correction is given by
\({\rm{Slope\;correction}} = \frac{{{{\rm{h}}^2}}}{{2{\rm{L}}}}\)
\({{\rm{C}}_{\rm{S}}} = \frac{{{{\left( {3} \right)}^2}}}{{2 \times 60}} = 0.075{\rm{\;m}}\)
CS = 0.075 m = 7.5 cm (Negative)
Note:
Correction due to slope will always be negative because slope distance is greater than corresponding horizontal distance.