Transcript Measurement Notes

Measurement Notes
Chapter 2 Section 1 & 2
Precision Vs. Accuracy
• Precision- is a description of how close
measurements are to each other.
• A clock with a second hand is more precise
than a clock with only a minute or an hour
hand.
Trials
Time (s)
Trials
Time (s)
Trial 1
34.5
Trial 1
30.1
Trial 2
30.1
Trial 2
29.8
Trial 3
29.2
Trial 3
29.5
Trial 4
37.0
Trial 4
30.3
Trial 5
36.6
Trial 5
30.0
A
Which is more precise?
B
Precision Vs. Accuracy
• Accuracy- Comparing a measurement to a
real, actual, or accepted value.
• A clock that is set ten minutes fast is not as
accurate as one that is set at the actual time.
The accepted value of the
acceleration due to gravity is
9.8 m/s (squared)
Which trial is the most accurate?
Trials
Acceleration
(m/s squared)
Trial 1
10.0
Trial 2
12.5
Trial 3
13.4
Trial 4
9.9
Trial 5
9.0
International System of
Measurement BASE UNITS
• In 1960 this became
the accepted system
for measurement.
• This is the metric
system and is what is
commonly used in
science.
Quantity
Unit
Symbol
Length
Meter
m
Mass
gram
g
Temperature
kelvin
K
Time
Second
s
Electric current
Ampere
A
Amount of substance
mole
mol
Liquid Volume
Liters
L
Solid Volume
Cubic
meters
m^3
newtons
N
Weight
International System of
Measurement
• Prefix Chart
– Common Prefixes
• Kilograms: kg
• Milliliters: mL
• centimeters: cm
Prefix
Multiplier
kilo-
1,000
hecto-
100
deka-
10
[Unit]
1
deci-
0.1
centi-
0.01
milli-
0.001
Note Activity Time
•
Mnemonic Device Definition: A mnemonic device is a sentence that helps us to
memorize a string of words. For example, music students use "Every Good Boy Does
Fine" to remember the order of notes on the treble clef. (E, G, B, D, F). Math
students use "Please Excuse My Dear Aunt Sally" to remember the order of
arithmetic operations (Parentheses, Exponent, Multiply, Divide, Add, Subtract.). But
the range of usefulness extends beyond music and math. They are an invaluable
resource whenever you are trying to remember something.
•
Directions: Your assignment is to create a mnemonic device for the standard metric
prefixes. You can be creative in the base unit area but all the other prefixes should
be accounted for in the device. Remember, the purpose of this is come up with
something that will always help you remember the correct order of metric prefixes
so make it something creative or meaningful to you. SCHOOL APPROPRIATE
Ex. King Henry Died Monday Drinking Chocolate Milk
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Kilo Hecto Deka (Base: Meter, Liter, Gram) Deci Centi Milli
Units
• Length- is defined as the distance between two points
• Volume- the amount of space an object occupies
• Mass- the amount of matter in an object
• Weight- measurement of force. Weight depends on
gravity and is measured in newtons (N).
• Temperature- physical property of how hot or cold
something is.
• Rate- amount of change of one measurement in a give
time. Example: (speed)