Civil Engineering - Surveying - Discussion

38. 

Offsets are measured with an accuracy of 1 in 40. If the point on the paper from both sources of error (due to angular and measurement errors) is not to exceed 0.05 cm on a scale of 1 cm = 20 m, the maximum length of offset should be limited to

[A]. 14.14
[B]. 28.28 m
[C]. 200 m
[D]. none of these.

Answer: Option B

Explanation:

No answer description available for this question.

Anvesh said: (May 14, 2015)  
How it will come?

Subhajit said: (Aug 18, 2015)  
s*r/(40*1.414).

= (20*40)/56.56.

= 14.14 answer.

Rajesh said: (Sep 4, 2015)  
Mention the formula clearly to calculate.

Ganpati Patel said: (Oct 16, 2015)  
L = s*r*error/1.414.

= 20*40*0.05/1.414 = 28.28 m.

Darshika said: (Dec 13, 2015)  
L = 0.05*s*r/1.414 = 28.28 m.

Ihab said: (Jan 14, 2016)  
Why 1.414?

Abhay said: (Feb 5, 2016)  
The center-to-center dimension for a 45-degree bend is equal to the desired size of the offset times the cosecant 1.414.

A cosecant is used to determine the distance between the centers of the two bends used to make an offset. A 45-degree angle has a cosecant of 1.414.

Satish said: (Aug 9, 2016)  
Due to angular & linear sin45 = 0.7 then it is 1.414.

Akhilesh Yadav said: (Feb 2, 2017)  
The displacement due to angular error =Lsin.
and it should be equal to displacement due to Linear error = L/r.
Corresponding displacement on paper=√2(L/r)(1/S)= √2(Lsin-/S).
Corresponding if a limit of accuracy in plotting is 0.05cm then,
√2(L/r)(1/S)=.05,
L= (.05x40x20)/√2.
= 28.28.
Where S=1 in accuracy.
r=1 in scale.

Naga Raju Gowd said: (Feb 15, 2017)  
How answer is 28.28?

I am not getting this. Please explain me.

Mohamed Elbesy said: (Apr 26, 2017)  
I think 200 is the correct answer.

1/40 accuracy on the map means 50 cm on the ground according to scale.
This means the offset is rounded to the nearest 50 cm and this applies only on 200 m.

Gaurav said: (Jul 4, 2017)  
Nowhere is mentioned that linear measurement is equal to angular measurement then, what is the reason to get answer 28.28?

Jay Panchal said: (Sep 11, 2017)  
Why 1.414?

Aashish said: (Sep 26, 2017)  
This formula is applicable maximum errorrs/√2.

28.28 correct answer.

Er Meghanada (Bhadrak) said: (Nov 12, 2017)  
L = 0.05"40"20*14.14 = 28.28 m.

Chandu said: (Dec 3, 2018)  
The maximum length or limiting length=L * S/sin0.
S=scale,
0=45°

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