### Discussion :: Surveying - Section 1 (Q.No.42)

Sandeep said: (Aug 28, 2013) | |

(1.5)2 / 2x3000 = 3.75 cm. Note: Length 30 m, gradient 1/20 ; h= 1.5. Equation : h2/2l. |

Hitesh Kumar said: (Jan 17, 2014) | |

Slope correction= h/2*2l. |

Priya said: (Oct 31, 2014) | |

Can any one explain this properly? |

Dash said: (Dec 18, 2014) | |

What is Gradient? |

Ahishek said: (Dec 29, 2014) | |

How h = 1.5? |

Anil Soni said: (Jan 14, 2015) | |

For 20 m, h = 1 m. So for 30 m, h = 1.5 m. |

Pranab said: (Mar 4, 2015) | |

h = 1.5 m & l = 30 m. So that = h2/2l = (1.5)2/2*30 = 0.0375 cm. |

Prashant said: (Mar 25, 2015) | |

(H2/2L)+(H4/8L3) as gradient is 1 in 20. i.e For 20 m, h = 1 m. So for 30 m, h = 1.5 m which is less than 3 m. Therefore second term of equation should be neglected. Answer is (1.5)2/2x3000 = 3.75 cm. |

Engr Attaullah Khan Tareen said: (May 6, 2015) | |

For 20 m, h = 1 m. So for 30 m, h = 1.5 m. So that = h^2/2l = (1.5) 2/2*30 = 0.0375 m. 1 m = 100 cm so 0.0375*100 = 3.75 cm. |

Maheshkumar said: (Jun 3, 2015) | |

In 1 in 20 means, 20m = 1m. So total 30m length = 1.5m. In Gradient 1 in 20 Means. Imagine Triangle, length-30m & Height-1.5m. Use Pythagoras theorem. X2 = 302+1.52. X = 30.0375m. Change length = 30.0375-30. = 0.0375m. = 3.75cm. |

Kanhu said: (Jul 24, 2015) | |

Slope correction for a sloping ground = h^2/2l. Where h = height. l = length of the ground. |

Ali said: (Apr 8, 2016) | |

We know for 30 m length, h = 1.5 And given gradient is 1 in 20 i.e 1/20 So, the equation of slope correction is, = h^2 / 2l = 1.5^2 / 2*30 m = 2.25 / 60m = 0.0375 m or 3.75 cm |

Swamy said: (Aug 31, 2016) | |

Hi, friends all give the good explanations. Thank you. |

Hima Bindu said: (Sep 23, 2016) | |

How h =1.5? |

Md Faisal said: (Nov 3, 2016) | |

In ABC triangle, AC = l = 30m. Slope = 1 : 20. 1 in20 so in 30 = (1/20) * 30 = 1.5 Therefore BC = 1.5m. And AB extends to BB'. And meet to points A as arc & B as a straight line. Here BB'= correction of line, = AC - AB. AB = (30^2 - 1.5^2)^1/2 = 29.962m. BB' = 30 - 29.962 = 0.0375m or 3.75cm. |

Baloch said: (Nov 28, 2016) | |

Slope correction = h^2 / 2l. h = 20/30 = 1.5. l = length. By submitting the value you will get the answer. |

Nawa Raj Budha said: (Dec 12, 2016) | |

Good explanations friends. Thank you. |

Sanjukta said: (Dec 17, 2016) | |

Thank you for the explanation friends. |

Bhupendra Murariya said: (Feb 3, 2017) | |

Not understanding, Please give the correct explanation for this question. |

Sunny Thakur said: (Mar 27, 2017) | |

Thanks for the explanation friends. |

Harsh Rathod said: (Jun 3, 2017) | |

Thank you all for your explanation. |

Swethakondisetty said: (Jun 27, 2017) | |

Slope correction =h^2/2l. |

Juhi said: (Jul 13, 2017) | |

Thank you all for your explanations. |

Sathya said: (Jul 16, 2017) | |

30 m length, h = 1.5. Given gradient is 1 in 20 i.e 1/20. The equation of slope correction is, = h^2/2l. = 1.5^2 / 2*30 m, = 2.25 / 60m, = 0.0375 m or 3.75 cm. |

Vijay Bhaskar said: (Dec 5, 2017) | |

How h= 1.5? |

Avijit Patra said: (Jan 16, 2018) | |

Here, l= 30 m. Gradient= 1 in 20, i.e h= 30/20= 1.5 We know, slope correction (Ch)= - h^2/2l = - (1.5)^2/(2*30) m. = -3.75 cm. |

Asad Ali Chandia said: (Jan 22, 2018) | |

Slop correction Formula = h^2/2*L. h = 30*(1/20) = 1.5 Hence, correction = 3.375 cm. |

Abhinandan Kumar said: (Mar 13, 2018) | |

1 in 20 means 0.05, So in 30 means 0.05*30=1.5(which is h), And we know the formula for a lope correction =h^2/2L, So 1.5^2/2*30=0.0375m and in cm. We get 3.75 m. |

Rasheedrash79 said: (Mar 28, 2018) | |

How are they getting 1.5*2=2.25? Please explain. |

Sameer Sopori said: (May 2, 2018) | |

h^2/2L. h= 1.5 (because of 1:20, 1/20 * 30 = 1.5), h= 2.25/60, h= 0.375m, h= 0.375 * 100, h= 3.75cm. |

Samadhan said: (May 14, 2018) | |

Slope means= just an inclined line. always 1st value indicates vertical distance & 2nd indicates horizontal distance...So h=1.5 how? see h=(V/H.), where V=vertical distance H=Horizontal distance. So, first Given(1 V/20 H)=(1/20)=0.05 this value in meter (we calculated slope length for 1 meter but given(30m), h=height between two endpoints of the slope. We have to calculate for 30 m) so just multiply =0.05*30=1.5 m Now, don't use (h^2/2L) formula it's approx. By using the formula, we get 0.03752346684 in meter now in option all value in cm. So just convert in cm = 3.75234668427 answer. h=height between two endpoints of the slope, hope this concept is clear. |

Mamatamayee said: (May 19, 2018) | |

Thanks for the explanation. |

Samadhan said: (May 20, 2018) | |

The exact formula is = (L- √(L^2-h^2)) Now in words Where L=length and h =meaning is same as above, L=30m And h=1.5m.. |

Aditya Singh said: (May 28, 2018) | |

Let me clearly explain this for those who are confused. The formula for slope correction is; C=h^2/2L. Now since grade is given is 1 in 20. That means for 20 m horizontal movement there will be a movement of 1m vertical..therefore accordingly for 30 m it will30/20 =1.5m. Now, put this into the formula and you will get 3.75 as answer. |

Kiran said: (Jun 12, 2018) | |

Thank you all for explaining the solution. |

Gulshan Kumar said: (Jun 27, 2018) | |

But 30 M is along the gradient, not horizontal distance. So, the value of h won't be exactly 1.5 M. |

Shubhajit Chakrabarty said: (Sep 9, 2018) | |

Let me clearly explain, tanθ = height/ base. => tanθ = 1/20, =>θ = 2.86. Now actual slop correction = l(1-cosθ). => 30(1-cos2.86) = 0.0373m. => 3.73 cm. |

Manoj said: (Nov 5, 2018) | |

Here h= 1.5, it is not correct because here 30 m is hypotenuse (i.e. equals to L , which is also used in slope correction formula ) but why use as a base or horizontal for finding h? Please explain me. |

Manoj said: (Nov 5, 2018) | |

By using of similarity of the triangle. H = 30÷401 and putting into slope correction formula. |

Omgir said: (Nov 9, 2018) | |

Helpful explanation. Thank you all. |

Don Chandu said: (Jun 1, 2019) | |

For 20 m vertical 1m. For 30m h = 30/20 = 1.5. Slope correction = h^2/2l = 1.5^2/(2 * 30) = 0.0375m = 3.75cm. |

Ritesh Kumar Singh said: (Jul 15, 2019) | |

Thanks for the explanation @Shubhajit Chakrabarty. |

Sindhu said: (Aug 8, 2019) | |

If 30m replace 60m then h=? |

Sathya said: (Aug 8, 2019) | |

@Sindhu. It is 0.075. |

Karn Chaurasiya said: (Sep 10, 2019) | |

150/ n^2 because 30 metre chain used and now slope current is 150/ 20^2 = 150 รท 400 = 0.375 m or 3. 75 cm. |

Charan Singh Majhi said: (Nov 8, 2019) | |

Slope correction = h^2/2l = 1.5^2/2*30 = 0.0375mtr = 3.75cm. |

Ankit said: (Jan 12, 2020) | |

Slope correction is negative or positive? Give details about it. |

Adarsh Krishna said: (Feb 19, 2020) | |

h^2/2l = 1.5*1.5/(2*30) = .0375m its change cm. = 3.75cm |

Adarsh said: (Feb 19, 2020) | |

Slope correction is always negative. |

Lav Kumar Yadav said: (Feb 21, 2020) | |

Slope correction =h^2/2L. So, 1:20. 20m=1m. 1m=1/20m. 30m=1/20*30=1.5. H= 1.5. (1.5) ^2/2*30=0.0375m. = 3.75 cm Answer. |

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