# Measurements

**Topics:**Measurement, Units of measurement, International System of Units

**Pages:**3 (477 words)

**Published:**January 26, 2013

The first experiment focused on the concept of errors and uncertainties that are obtained during measurements. For an experiment to be successful, especially those that involve measurements, the number of significant figures must be known. Significant figures are the digits required to express a measured quantity and thus reflect the accuracy of the measurement. Uncertainty is defined as the smallest increment that can be measured and is defined by the instrument used. An error is defined as any deviation from the standard value. Errors could either be systematic or random. Systematic errors are caused by measurements that are not properly calibrated while random errors are caused by chance.

Methodology

Figure 1: Experimental set-up using vernier caliper

Figure 2: Micrometer caliper

In the experiment, three measuring devices are used to obtain the measurement of a sphere with known composition: vernier caliper, micrometer caliper and a foot rule. Ten individual measurements are then made for each of the device. After the measurements are obtained, the mean diameter of the sphere was calculated using the formula: Mean Diameter = Σdiameter

n

Using this data, the deviation of each measurement was calculated,

d = /reading – mean diameter/

as well as its average deviation

(a.d.) = Σd

n

The volume and the density of the sphere were then calculated using the appropriate formula.

Volume (V) = 4/3πr2

Density = mass

volume

Lastly, the percentage error was determined to show how accurate the measurements have been. %Error =

|experimental value – true value| x 100

|true value|

Theory

The displacement Δx of an object is defined as its change in position and is given by

Δx ＝xf – xi

where xi refers to the initial position of an object and xf refers to the final position of an object and its unit is expressed in meter (m).

The average speed of an object over a given length of time...

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