Kids are naturally curious, so it’s an ideal time to teach them about objects and the world around them. This includes the concept of mass.
Mass is a measurement of matter and is measured in kilograms and other units. It determines the strength of an object’s gravitational attraction to other objects, its resistance to acceleration due to a force and its inertia.
Physical
Mass is an intrinsic property of matter and inextricably tied to weight. Because of this, a device calibrated to a standard measurement of mass can also measure an object’s weight. For example, a balance scale measures your weight by comparing your mass to the mass of a metal cylinder kept at NIST called the United States Prototype Kilogram. This international standard, part of the metric system, is what defines a kilogram (kg) and a tonne (metric ton).
In general, the more matter in an object, the greater its mass. This is because the object has more resistance to change in its speed or position due to an applied force. Mass is conserved, however, even when matter particles are converted to non-matter particles such as photons of light or heat. This fact is an essential foundation for energy analysis and atomic and molecular research, as it means that a measurement of an atom or molecule’s mass will give the same results regardless of its surroundings.
Chemical
With modern mass spectrometers, the precise chemical structure or peptide sequence of an unknown compound can often be deciphered by comparing its experimental mass spectrum to a library of known masses. This is usually achieved by a combination of manual and software-assisted interpretation of the fragmentation pattern using a priori structural information.
It is important to statistically treat accurate mass data and that correct terminology is used. The following is a summary of terminology and basic statistical procedures to be adopted in such work.
Mass lists quoted in Da, mDa, mu (milli u) or ppm should always be given to at least one decimal place to avoid rounding errors that can occur. Mass measurement accuracy (MMA) is an average of n individual error values, Dmi, and includes the sign so that positive and negative errors partially cancel. It is sometimes also referred to as mean error or mass error. The root mean square error is a similar statistic but differs from MMA in that it does not include the sign.
Quantitative
In many applications, scientists desire to know the relative or absolute concentration of an analyte in a sample. This is often necessary in biological specimens because the chemical localization of analytes in these tissues is vital for drawing accurate biological conclusions.
Mass spectrometry provides an effective tool for the measurement of sample concentration. It presents data as a mass spectrum, a plot of intensity against the mass-to-charge ratio (m/z) of ions, which can be useful in the identification of an element or compound, or for determining its structural characteristics.
Some types of mass spectrometry data can be presented as a chromatogram, where the m/z is on the x-axis and the intensity is recorded on the y-axis. Other types of data are best represented by a contour map. Several analyzer characteristics affect the quantitative capabilities of MS, including its m/z resolution, mass accuracy and linear dynamic range. The latter is usually defined as the maximum value of a sample peak divided by the peak maximum on a calibration curve made from spiked samples of known concentration.
Geometric
Geometry is a discipline that studies two-dimensional geometric shapes and their relationships. It involves understanding, visualizing and representing shapes; identifying characteristics and properties of these shapes; and analyzing and manipulating them.
The geometry of a set of numbers can be determined by the geometric mean, which is defined as the nth root of the product of the elements. For example, the geometric mean of the numbers 1
Objects with irregular shapes are more challenging to measure. Using measurement tools with precision is key to avoid errors. Also, it is important to use consistent units. For example, mixing grams and liters can yield inaccurate results.
Using an inertial balance scale can help determine mass, but the scale must be calibrated carefully to get accurate measurements. It is also possible to convert from mass to weight using Newton’s second law of motion, which relates force and acceleration by the equation F = ma.