1. The Language of Physics
The Science of Physics
The Language of Physics

2. Mathematics and Physics
Physicists use mathematics to analyze and summarize their observations
Use mathematical relationships among physical quantities to help predict what will happen in new situations
Use tables, graphs, and equations

3. Mathematics and Physics
Physics equations indicate relationships
Use letters to describe specific quantities
v often stands for velocity or speed
Variables use bold or italics to distinguish them from units which use regular type
Greek letters often describe a mathematical operation
Delta (Δ) means “difference” or “change in”
Subtraction
Sigma (Σ) means “sum” or “total”
Addition

4. Direct Proportions
Directly proportional – when dividing two sets of quantities by one another gives a constant value
Graphs as a straight line that passes through (0,0)
Can be expressed y x which reads y is proportional to x
y/x=k or y=kx.
When x increases, y increases and vice versa

5. Inverse Proportions
Inversely proportional – when two sets of quantities have products that are constant
Graphs as a curve called a hyperbola
Can be written as y /x which can be read as y is proportional to one divided by x
xy=k
When x increases, y decreases and vice versa

6. Dimensional Analysis Treat dimensions like algebraic variables
Can rearrange them in equations by performing the same operation to both sides
v = d / t
Solve for t

7. Dimensional Analysis v = d / t Multiply both sides by t
t * v = d / t * t
t’s on the right side cancel out
t * v = d

8. Dimensional Analysis t * v = d Divide both sides by v
(1 / v) * t * v = d * (1 / v)
v’s on the left side cancel out
t = d / v
Plug in numbers

9. Order-of-Magnitude Gives you a ballpark estimate
Useful if you don’t have a calculator
Use power of 10 closest to actual numbers instead of actual numbers
d = 725km
v = 88km/h
t = ?

10. Order-of-Magnitude
d = 725km ≈ 1000km
v = 88km/h ≈ 100km/h
t = d / v

11. Order-of-Magnitude t ≈ 1000km / 100km/h ≈ 10h