Civil Engineering - Surveying - Discussion

42. 

The slope correction for a length of 30 m along a gradient of 1 in 20, is

[A]. 3.75 cm
[B]. 0.375 cm
[C]. 37.5 cm
[D]. 2.75 cm.

Answer: Option A

Explanation:

No answer description available for this question.

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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