Revised 4/4/11
Name: __________
Hour: __________
RULER LAB – Part 2
PROBLEM TO STUDY: To study how the uncertainty of a measurement effects a
multiplication or division calculation and determines how many digits to keep in that
answer.
Action
1. Take the measurements of the shelf board from the first ruler lab.
2. Calculate the area of the largest surface using all three of the meter
sticks.
3. Calculate the area of the smallest surface using all three meter
sticks.
4. Get into a group of two or three people and design a way to find
out how an estimated digit of a measurements influence the
calculated areas of the shelf.
Hypothesis: If a measurement has 3 significant Figures (meaning the third digit is
uncertain), then the ________ digit in a calculated answer will be
uncertain.
Steps taken - Write down the steps the group took
1
Revised 4/4/11
DATA:
Data table from first ruler lab
Smallest Division on
Length of Shelf
Ruler
1 meter
100 cm
80
1 decimeter 10 cm
79
1 millimeter
0.1 cm
Width of Shelf
78.99
Calculating Area of Largest side
Smallest Division on
Length of Shelf
Ruler
1 meter
100 cm
1 decimeter 10 cm
1 millimeter
30
29
NA
3
28.98
2.65
Width of Shelf
Area
depth of Shelf
Area
0.1 cm
Calculating area of smallest side
Smallest Division on
Width of Shelf
Ruler
1 meter
100 cm
1 decimeter 10 cm
1 millimeter
Depth of Shelf
0.1 cm
Add data tables for the experiment here.
2
Revised 4/4/11
Which measurement, the length or width creates more uncertainty in the calculated
answer?
Which measurement, the width or depth creates more uncertainty in the calculated
answer?
Based upon the idea that a calculated answer should only have one uncertain digit and all
the rest should be rounded away, how should the calculated value of the area be rounded?
Write down the value correctly rounded.
ANALYSIS:
Working with your group, write a general rule that states clearly how to determine the
number of significant Figures should be kept in the answer of a multiplication and
division process.
If a number which has 2 Significant figures is divided by a number with four significant
figures, how many significant figure should the answer have?
3
Revised 4/4/11
Complete the following calculations and round to the correct number of Sig. Figs.
1.
m  DV
m  13.62 g mL  79mL
m
2.
m
V
2.6g
D
371mL
D
D

 3.
m
D
9468g
V
0.789 g mL
V
V

How many significant figures are in the following numbers.
1.
3000
2.
2060
3.
200
4.
200.
5.
200.0
6.
0.0200
7.
0.0203
8.
0.02030
9.
2.0 X 102
10.
4.2 X 10-7
4