# 1: Nature of Physics


• 1.1: The Basics of Physics
Physics is a study of how the universe behaves.
• 1.2: Scientific Notation and Order of Magnitude
Scientific notation is a way of writing numbers that are too big or too small in a convenient and standard form.
• 1.3: Units and Standards
Systems of units are constructed from a small number of fundamental units, which are defined by accurate and precise measurements of conventionally chosen base quantities. Two commonly used systems of units are English units and SI units. SI units are a metric system of units, meaning values can be calculated by factors of 10. The SI base units of length, mass, and time are the meter (m), kilogram (kg), and second (s), respectively.
• 1.4: Unit Conversion
Multiplication by conversion factors allows for quantities to change units. The operation must be done in such a way that the units you want to get rid of are canceled and the units you want to end up with remain. Units obey the rules of algebra so, for example, if a unit is squared two factors are needed to cancel it.
• 1.5: Dimensional Analysis
The dimension of a physical quantity is just an expression of the base quantities from which it is derived. All equations expressing physical laws or principles must be dimensionally consistent. This fact can be used as an aid in remembering physical laws, as a way to check whether claimed relationships between physical quantities are possible, and even to derive new physical laws.
• 1.6: Significant Figures
Accuracy of a measured value refers to how close a measurement is to an accepted reference value. Precision of measured values refers to how close the agreement is between repeated measurements. Significant figures express the precision of a measuring tool. When performing mathematical operations with measured values, there are rules to standardize the precision of the final answer.
• 1.7: Summary
• 1.8: Exercises