1. Starter Get out: 1. HW booklets and put on front desk in neat pile
2.PAG laboratory book (from box at back) and look at marking of your last PAG.

2. Lesson Goals Review and evaluate experiment to calculate g.
Learn how to use Vernier Callipers and Micrometer Screw Gauge correctly and to evaluate unceratinty in measurements.

3. Measurement
Actual uncertainty
Percentage uncertainty
Proposed changes to method to improve uncertainty. If any possible.
Drop Height measured with a ruler.
±0.01m
= 0.01/1.50 x 100
= 0.7%
Use a horizontal fixed bar to give more precise start position, reduce uncertainty to ±0.001m therefore 0.07%
Manual timing of drop
±0.2s due to reaction time
Measurement of laminated strips
Measurement of times using light gates and datalogger

4. How to use Vernier Callipers
2cm
2.1cm
2.13cm
2.13 ±0.01cm

5. You try
What does this show? Be careful…
10.02±0.01cm

6. How to use Micrometer

7. You try
2mm
2.88 ± 0.01mm
2.5mm mm

8. Now try
Measure various items in the lab – choosing the correct equipment for the size of measurement.
Record in your lab books two tables one for Vernier Callipers (below) one for Micrometer (careful about units!)
Measurement
Length 1 /cm
Length 2 / cm
Length 3 / cm
Average length /cm
% uncertainty