Module 5 Linear Measurments Corrections

Question 1

Correction due to length ?

Answer 1

CD=MDxATL/GTL

CD- correct distance (length)

MD- measured distance (length)

ATL- actual tape length

GTL- graduated take length

GTL - too short -

Too long +

Question 2

Correction due to temperature ?

Answer 2

Ct=Lxe(tm-ts)

• CD=L+ct (above standard temp)
• CD=L-ct (bellow standard temperature)

Ct- temperature correction

L-measured distance

E-coefficient of linear expansion

Tm-measured temperature

Ts-standard temperature

Question 3

Correction due to slope?

Answer 3

Sc=L(1-cos0)

CD=L-sc

Sc= slope correction

L= measured distance

0= slope angle

Question 4

Correction to due sag ?

Answer 4

Cs=w2L2/24T2

CD=L-cs

Cs=sag correction

W= mass of tape (kg/m)

L=measured length

T=measured tension (kgf=10n)

Question 5

Correction due to height above sea level ?

Answer 5

Ch=LxH/R

CD=L-CH (above sea level)

CD=L+H (below sea lebel)

CH=correction

L=measured length (distance)

H= height above or below sea level

R= earth radius (convert km to m)x100

Question 6

Correction due to tension ?

Answer 6

Cp=1m(p-Po/ae) cp=1m(pm-ps/ae

E- modulus of elasticity of steel

Cp- tension correction

P= applied tension (pm) in N

Po= standard tension (ps)

1m= length of tape in mm

Ae = cross section of tape in mm area