1. The Language of Physics
Pearland ISD Physics
Mark Lesmeister

2. Objectives Interpret data in tables and graphs.
Distinguish common symbols used in equations.
Recognize common equations and graphs.
Convert units.
Use dimensional analysis.

3. Tools to make data easier to understand.
Tables
Very useful for displaying data precisely.
The relationship between the quantities may not be clear.
Graphs
Visually display the relationship between two quantities.
The precision of the data is limited by the scale of the graph.

4. Tools to make data easier to understand.
Equations
Mathematically display the relationship between two quantities.
Can be manipulated using algebra:

5. Relating equations and graphs

6. Symbols used in physics equations
S means “sum” or “total.”
D means “difference” or “change in.”
Quantity
Symbol
Units
Unit
Abbrev.
Change in position
Dx , Dy
meters m
Time interval Dt
seconds s
Mass
kilograms kg

7. Evaluating physics expressions
Units are treated like other algebraic quantities in equations.
Ex.: A car travels 20 m/s for 120 s. How far does the car travel?

8. Dimensional analysis
Dimensional analysis- determining what units would result from a calculation. In order to be correct, a calculation must produce units of the proper dimension.
Ex.

9. Order of Magnitude Calculations
Order of magnitude calculations are estimates made using orders of magnitude, that is, powers of 10.
Ex.- How long is PHS, as an order of magnitude?

10. Converting units
To convert units, multiply the quantity you wish to convert by fractions equalling one; that is, fractions with equivalent units in the numerator and denominator.
For example, convert 20 m/s to km/hour.