View
235
Download
0
Category
Preview:
Citation preview
Chapter One: Measurement
1.1 Measurements
1.2 Time and Distance
1.3 Converting Measurements
1.4 Working with Measurements
Section 1.4 Learning Goals
Determine the number of significant figures in measurements.
Distinguish accuracy, precision, and resolution.
Compare data sets to determine if they are significantly different.
Accuracy vs. Precision
Accuracy is how close a measurement is to the accepted, true value.
Precision describes how close together repeated measurements or events are to one another.
Resolution Resolution refers to the smallest interval that can be measured.
You can think of resolution as the “sharpness” OR “greatest number of divisions” of a measurement.
Since clock has minute marks,
resolution is 0.5 min.
Graduated cylinder:0.5 ml
Significant Differences In everyday conversation, “same”
means two numbers that are the same exactly, like 2.56 and 2.56.
When comparing scientific results “same” means “not significantly different”.
Significant differences are differences that are MUCH larger than the estimated error in the results.
Dropping Ball Experiment1. Use stop watch to time how long the ball is in
the air.2. Repeat two more times.3. Are all three times EXACTLY the same? 4. What is same? Different?
5. Average your trials.6. Is average same as everybody else?7. What is same? Different?
What is the REAL answer? In the real world it is
impossible for everyone to arrive at the exact same true measurement as everyone else.
What is the length of thepaper clip in centimeters?
2.63 cm
How many digits/decimal places are enough?
Digits that are always significant:1. Non-zero digits (9 cm has one sig
fig).2. Zeroes between two significant
digits (902 cm has three sig fig’s).3. All final zeroes to the right of a
decimal point (902.0 cm has four sig fig’s).
Digits that are never significant:4. Leading zeroes to the right of a
decimal point. (0.009 cm has only one significant digit.)
5. Final zeroes in a number that does not have a decimal point (900 cm has one sig fig).
How many digits are
significant?
Final answer: 4.3
Final answer: 242 or 2.42 X 102
Calculation Rules
Solving Problems
What is area of 8.5 in. x 11.0 in. paper?
1. Looking for: …area of the paper
2. Given: … width = 8.5 in; length = 11.0 in
3. Relationship: Area = W x L
4. Solution: 8.5 in x 11.0 in = 93.5 in2
FINAL ANSWER: # Sig. fig’s= 94 in2
For Final
Answer, y
ou
need to figure
out how m
any
sig fig’s!
Final answer: 4.3
Final answer: 242 or 2.42 X 102
Calculation Rules
Scientific Notation
Simply a method (short hand for numbers) for
expressing and working with really big OR really
small numbers.
Recommended