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Questions and Answers
What does the most probable value (mpv) represent in a measurement?
What is accuracy in the context of measurement?
What does the residual represent in a measurement?
In surveying measurements, what does relative error precision measure?
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What is the purpose of Theory of Probability in measuring results?
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What defines the Probable Error in a measurement?
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Which of the following is a direct method of measuring horizontal distances?
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What is the definition of a pace in the context of distance measurement by pacing?
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What is the purpose of relative error or relative precision in measurement?
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Which method of measuring horizontal distances was introduced in 1771 by James Watt of Scotland?
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What is the length of the subtense bar used for measuring horizontal distances?
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Which method allows for the determination of unknown distances through their relationship with known distances geometrically?
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What is the process of determining the extent, size or dimensions of a particular quantity in comparison to a given standard?
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Which type of measurement is done when it is not possible to directly apply a measuring instrument to the quantity being measured?
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What is the international unit of linear measure?
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What is the difference between the true value and the measured value of a quantity called?
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What causes inaccuracies in measurements due to carelessness, inattention, poor judgment and improper execution?
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Which of the following is NOT a cause of errors in measurement?
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Study Notes
Measurement and Error
- Relative error is expressed as a fraction of the magnitude of the error in the numerator and the magnitude of the measured quantity in the denominator.
- The meter is the international unit of linear measure.
Methods of Measuring Distance
- Pacing involves counting the number of steps or paces in a required distance, with a pace being the length of a step in walking.
- Distance by Taping uses a graduated tape to measure horizontal distances.
- Distance by Tachymetry is an indirect method of measurement based on the optical geometry of instruments.
- The Stadia Method provides a rapid means of determining horizontal distances, introduced by James Watt in 1771.
- The Subtense Bar Method uses a 2-meter long bar to measure horizontal distances accurately.
Types of Surveys
- Route Surveys involve determining alignment, grades, earthwork quantities, and location of natural and artificial objects for linear projects.
- Topographic Surveys determine the shape of the ground and the location and elevation of natural and artificial features.
Measurement and Errors
- Measurement is the process of determining the extent, size, or dimensions of a quantity in comparison to a given standard.
- Direct Measurement compares a measured quantity with a standard measuring unit.
- Indirect Measurement determines a quantity by its relationship to other known values.
- Error is the difference between the true value and the measured value of a quantity.
- Mistakes are inaccuracies caused by carelessness, inattention, or poor judgment.
- Personal Errors arise from limitations of the senses of the human observer.
Accuracy and Precision
- Accuracy indicates how close a measurement is to the absolute or true value of a quantity.
- Probability theory is useful in indicating the precision of results affected by accident errors.
- The most probable value (mpv) is a quantity that has more chances of being correct than any other.
- The residual is the difference between a measured value and its most probable value.
- The probable error is a range within which there is a 50% chance that the true value of the measured quantity lies.
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Description
Explore different types of land surveys used in civil engineering projects, such as Route Surveys and Topographic Surveys. Learn about the process of measurement and its importance in determining the extent and size of land features.
