1. Physics – an experimental science
Physis (greek) means nature
We make models and use measurements to verify (or falsify) them

3. Make groups
Measure the length of the corridor

4. Measurements and uncertainty
The result of a measurement is a value AND a unit
Always give a reasonable precision
176.8 cm (four significant figures)
177 cm (three s.f.)
180 cm (two s.f.)
If possible, give the measurement error
5.0 ± 0.5 cm (absolute error)
5.0 ± 10% cm (relative error)

5. SI-system SI system: an international agreement on standard units
Based on 7 basic units
Quantity
Unit
Length s
Meter m
Time t
Second
Mass
Kilogram* kg
Electric current I
Ampere A
Temperature T
Kelvin K
Ammount of substance n
mole
mol
Luminous intensity
Candela cd
∗the only basic SI unit with a prefix
All other are derived units (combinations of the basic units)
Quantity
Unit
Velocity v
Meters per second
m s-1
Force F
Newton (= kilogram meters per second squared)
N (= kg m s-2)

6. We often need to convert between SI-units and other units
Ex. 1: a) how many meters are 2 ft? b) how many feet are 2 meters? (1 ft = m)
Ex. 2: How many km/h is 45 mph? (1 mile = 1609 m)

7. When dealing with large or small numbers we can use
Prefixes
Powers of ten
Ex. 3: Write m with: a) a prefix b) with a power of 10

8. In groups of 6-7: one drops a piece of paper, all the others time the fall. Save your results

9. Spreadsheets and graphs
Spreadsheets are used to calculate the average and an error for repeted measurements
Graphs are used to find patterns in connected measurements
Show clear data points (NEVER play ”connect the dots”!)
Add a line of best fit
If possible, show error bars

10. Important tools: Task: measure the Vernier calipers Micrometer
Stopwatch
Task: measure the
thickness of your hair
width of your shoe
time it takes for a shoe to fall from desk to floor