Civil Engineering - Surveying - Discussion

Discussion Forum : Surveying - Section 2 (Q.No. 14)
14.
The desired sensitivity of a bubble tube with 2 mm divisions is 30". The radius of the bubble tube should be
13.75 m
3.44 m
1375 m
none of these.
Answer: Option
Explanation:
No answer description is available. Let's discuss.
Discussion:
18 comments Page 1 of 2.

Roohullah jan said:   5 years ago
It's quite simple guys.

As we know S=R* π --->1)
Where R is radius and π is Central angle in radian.
So S= 2mm.
π= 30" remember 1"= 0.00000484814 so 30" becomes 30* 0.00000484814= 0.0001454441 rad.

Equation (1)=> 2=R*0.0001454441.
R= 13750.98mm => 13.75 m.
(3)

Shailendrabsingh said:   9 years ago
Angle = arc/radius or =(d/r) radians.

Because 1 Radian = 206265 second.
So, = (d/r) * 206265 second.
Given that d = 2mm or 2 * 10^-3m.
So, ={(2 * -10^-3) * 206265}÷ r.
Then @ = 412.53÷r.
Given, 30second.

So r = 412.53÷30,
r = 13.75meter.
(1)

Philven said:   3 years ago
The formula is radius equals to the [sensitiveness] divided by [division (in seconds) multiplied by sine 1 second].

Radius= 2mm/30"
= 13750.987 mm (convert to meters)
= 13.75.
(3)

Sameer Kashmiri said:   9 years ago
If 30 = 2mm.

Then 1 =60" =4mm.

Then 1degree = 60 * 4 = 240mm.

It means 360 degree = 360 * 40 = 86400mm.
= 86.4 m.

R = L/2 * 3.14.
R = 86.4/2 * 3.14.
R = 13.75 m.

Pinku said:   9 years ago
2mm deflect with a small change of angle 30''
30'' ---> 2mm
60'' ---> 4mm
1' ---> 4mm.

For 360degree ---> 360 * 60 * 4.
So, 2 * 3.14 * r = 360 * 60 * 4.
r = 13.75.

Chad Quincy Cablitas said:   3 years ago
Formulas:

alpha(") = s/nDsin1"
R = nLD/s.

Manipulating the formulas, we know that:
R = (1/alpha(")*sin(1"))*L,
R= 13.75.

MD FAISAL said:   8 years ago
In 30'----2mm.

So 360°=?
(360*60*60)'*2mm/30'=length of circumference.
So Lc=2*3.14*R.
(360*60*60)'*2/30'=2*3.14*R.
R=13.75m.
(2)

Moin said:   5 years ago
For 2 mm divisions,

sensitivity = 412.43/R.

This is a simple way to remember it. In general, sensitivity = 206265 * d/R.
(1)

Tanmoy karmakar said:   7 years ago
30'' = 2mm,
1' = 4mm,
1° = 240mm,
360° = 240*360 = 86400mm,
2*π*r = 86400,
So, r = 13757.9mm = 13.75 m.
(8)

Kesavan said:   7 years ago
Sensitivity = (D/R)*205265.
so, we need R=(D/sensitivity)*206265.
R = (0.002/30)*206265.
R = 13.75 m.
(9)


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