# The Metric System, Speed, and Acceleration ```Welcome to Physics:
A college preparatory
course.
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Course Expectations
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Cellphone = NO!!!!
– Scientific Calculator
– Notebook or Binder
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Webpage
Safety Contract – Signed
Warm-up
HW &amp; Review (Bonus Points)
Make up missed work
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Notes
Tests
Extra Help
Letters of recommendation
“Are you a student, or just a kid who comes to
school?”
Measuring
What will you study in physics (three things)?
What types of jobs may require a college
physics course?
What is the difference between a scientist and
an engineer?
Measuring
1
MKS system
Measuring
MKS – Meter-Kilogram-Second
Historical Pt-Ir meter bars
U.S. National Kilogram (NIST)
Seven Fundamental units
Cesium Fountain Clock at NIST
1,000,000 m
1,000 m
100 m
10 m
1m
1m
1m
1m
1m
=
1 Megameter (Mm)
=
1 kilometer (km)
=
1 hectometer (hm)
=
1 dekameter (dam)
=
1 meter
=
10 decimeter (dm)
=
100 centimeter (cm)
=
1000 millimeter (mm)
= 1,000,000 micrometers (mm)
Kilogram
Meter
Second
Candela
Ampere
Kelvin
Mole
Giga (G) = 109
Mega (M) = 106
kilo (k)
= 103
hecto (h) = 102
deka (da) = 101
deci (d) = 10-1
centi (c) = 10-2
milli (m) = 10-3
micro (m) = 10-6
nano (n) = 10-9
pico (p) = 10-12
2
Metric Examples
a. How many meters is 55 cm?
b. How many milliliters is 0.0250 liters?
c. How many kilograms is 13405 mg?
(0.013405 kg)
d. How many milliseconds is 0.0450
hectoseconds? (4500 ms)
The Metric System
Examples:
600 nm
0.0055 Gs
5677 kg
Metric Practice Examples
The Metric System
Examples:
600 nm
0.0055 Gs
5677 kg
10-7
=6X
m
= 5.5 X 106 s
= 5.67 X 106 g
Metric Practice Examples
a)
b)
c)
d)
e)
f)
g)
4658 cm
635 cm
553 ms
0.0023 kL
0.468 cm
7200 cs
10800 s
=
=
=
=
=
=
=
0.04658 km
0.635 dam
5.53 ds
2300 mL
4.68 mm
7.2 das
3 hours
=?m
=?s
=?g
a)
b)
c)
d)
e)
f)
g)
4658 cm
635 cm
553 ms
0.0023 kL
0.468 cm
7200 cs
10800 s
=
=
=
=
=
=
=
? Km
? Dam
? ds
? mL
? mm
? Das
? hours
Metric Example 5
How many square meters is 685 cm2?
685 cm2 1 X 10-2 m
1 cm
685 cm2 1 X 10-2 m 1 X 10-2 m
1 cm
1 cm
685 cm2 1 X 10-2 m 1 X 10-2 m = 0.0685 m2
1 cm
1 cm
3
Metric Example 6
Metric Example 7
How many square decimeters is 0.250 m2?
0.250 m2 10 dm
1m
How many cubic centimeters (cm3) is
0.00453 m3?
0.0453 m3
0.250 m2
10 dm
1m
10 dm
1m
0.250 m2
10 dm
1m
10 dm = 25.0 dm2
1m
100 cm
1m
100 cm
1m
(Ans: 4530 cm3)
Challenge
Problem
The tallest building in
the world is the
Burj Kalifa, Dubai.
It is 828 meters
tall. How many
feet is that?
100 cm
1m
Metric Example 9
Convert 22 miles/hour to m/s.
22 miles
1 hr
1.61 km 1X103m 1 hr 1 min = 9.8 m/s
1.00 mile
1 km 60 min 60 s
(1 inch = 2.54 cm)
(2717 ft)
Metric Example 10
Metric Practice Examples
Convert 200. cm/s to miles/hour.
200. cm
1s
1X10-2 m 1 km 1.00 mile 60 s
1 cm
1X103 m 1.61 km 1 min
60 min
1 hr
55 mi/hr
55 mi/hr
65 miles/hr
400 cm/s




km/hr
meters/min
meters/s
miles/hr
= 4.47 miles/hr
[1.000 mile = 1.609 km]
4
Metric Practice Examples
55 mi/hr
55 mi/hr
65 miles/hr
400 cm/s




89 km/hr
1476 meters/min
29.1 meters/s
8.94 miles/hr
Accuracy and Precision
Accuracy
– how close the average of a set of measurements
is to the true value
– Measured using Percent Error
Students did trials to measure the density of a
metal. The accepted density is 7.2 g/cm3.
Were they accurate or precise?
Precision
– How close a set of measured values are to one
another
– Measured using Range
– Highest - lowest
A student measures the melting point of a
sample of beryllium and does four trials.
The trials result in melting points of 1267 oC,
1245 oC, 1270 oC, 1255 oC. Calculate the
percent error ,range and comment on
accuracy and precision. (accepted = 1278
oC.)
Set 1
Set 2
Set 3
7.21 7.25 7.18
6.40 7.90 7.30
6.45 6.52 6.48
A student measures the density of a sample of
lead and does four trials. The trials result in
densities of 11.3, 10.5, 11.9, 10.8 g/cm3. The
accepted density of lead is 11.4 g/cm3.
Comment on accuracy and precision by
calculating the percent error and the range.
5
Hypothesis
Scientific Method
Hypothesis – testable, educated guess
Theory
Theory - repeatedly confirmed hypothesis that
has predictive power.
Law
Law – Theory with NO known exceptions
Control Vs. Experimental
Groups
• Control – Nothing happens to control group
• Experimental – Change ONE variable
Example: Plant growth
Control
Experimental
1. Based on Anecdotal Evidence
Anecdotal - From stories, not studies (no
math)
2. Small Sample Size
3. Not published in Journals – not reviewed
or tested
Example: The Water Cure
16a) 1.5 X 1011 m b) 150 Gm
32a) 0.10 nm
c) 1.0 X 1010 A
b) 1.0 X 105 fm
d) 9.5 X 1025 A
42a) 1.00 X 109 cm3
c) 6.10 X 107 in3
b) 3.53 X 104 ft3
SCIENCE IS REPRODUCIBLE
6
• http://theuniverseandmore.com/
g-man
• http://jersey.uoregon.edu/block/Block.html
• http://www.cabrillo.edu/~dbrown/tracker/
A 250 cm
G 5.678292
km
M 3.15 X 107 S 2153 ft2
s
B 420 mm
H 1.2 cm
N 29.1 m/s
C 46.7 m
I
D 0.500 A
J 2470 cm
E 5.5 X 10-7
m
K 2.68 X 109 Q 516 cm2
s
F 3.11 miles
L 4.8 cm
0.0862 km O 62.1 mph
P 78.3 mph
T 18.6 m2
U 6540 yd3
V 61.0 in3
R 0.052 m2
List three specific things TO DO to be