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Q: The error in measured length due to sag of chain or tape is known as ______.
  • A. Positive error
  • B. Negative error
  • C. Compensating error
  • D. Instrumental error
Correct Answer: Option A - Sag in chain (cumulative +ve)– When the distance is measured by 'stepping' or when the chain is stretched above the ground due to undulations or irregular ground, the chain sags and takes the form of a catenary. The measured distance is, therefore, too great and the error is cumulative and positive. The location of an object is determined by sighting at the object from two plane table stations (previously) plotted and drawing the rays. The intersection of these rays will give the position of the object.
A. Sag in chain (cumulative +ve)– When the distance is measured by 'stepping' or when the chain is stretched above the ground due to undulations or irregular ground, the chain sags and takes the form of a catenary. The measured distance is, therefore, too great and the error is cumulative and positive. The location of an object is determined by sighting at the object from two plane table stations (previously) plotted and drawing the rays. The intersection of these rays will give the position of the object.

Explanations:

Sag in chain (cumulative +ve)– When the distance is measured by 'stepping' or when the chain is stretched above the ground due to undulations or irregular ground, the chain sags and takes the form of a catenary. The measured distance is, therefore, too great and the error is cumulative and positive. The location of an object is determined by sighting at the object from two plane table stations (previously) plotted and drawing the rays. The intersection of these rays will give the position of the object.