1. Measurement

2. Measurements
Always have some degree of uncertainty that needs to be indicated
Record results to the appropriate number of significant figures; this includes all certain digits and the first uncertain (estimated) digit

3. Measuring with a Ruler Measuring error = 1/10 of smallest division
Reading error is equal to 1/10 of the smallest division on the ruler

4. Practice

5. **Measure from the bottom of the meniscus
Measuring a Liquid
**Measure from the bottom of the meniscus

6. Practice
ii. i.

7. iv.
iii.

8. How close a measurement is to a known or accurate value
Accuracy vs Precision
How close a measurement is to a known or accurate value
How close measurements are made to each other; reflects reproducibility

9. Jack has a height of 70 inches. Which sets of measurements are
Example
Jack has a height of 70 inches. Which sets of measurements are
Accurate and precise (A/P)
Precise but not accurate (P)
Neither precise nor accurate (N)
69.5 in., 70.5 in., 70.1 in.
45.3 in., 62.1 in., 84.3 in
78.3 in., 78.0 in., 78.1 in

10. Percent error
error
Percent error =  exp val – act val  x 100%
act val
Example: Your data reads 99.1g but the accepted value is 101.0g, what is your percent error?