Chapter 2 - Measurement
Section 2 – SI Units
Pages 50 - 54
The International System
• Sharing data and information around the world
would be complicated if everyone used different
measuring systems.
• Scientists established the International System
of Units or SI units to provide a worldwide
standard.
• SI units are related by multiples of tens
tens.
• SI units help accurately and precisely measure
physical properties.
properties
SI Base Units – Length
• Length is defined as the distance between two
points.
• The meter is the base SI unit for length.
• The abbreviation for a meter is m.
• One meter is about the size of a baseball bat.
bat
• Some instruments that are used to measure
length include a ruler or a meter stick.
SI Base Units – Volume of a Solid
• The amount of space an object occupies is its volume
volume.
• The cubic centimeter is the base unit for solid volume.
• The abbreviation for the cubic centimeter is cm3.
• The instrument that is used to measure solid volume is
the ruler or meter stick.
stick
• The solid volume of an object is equal to: length * width
* height.
• Example: Volume of the box =
5 cm * 11 cm * 2 cm = 110 cm3
SI Base Units – Volume of a Liquid
• The liter is the base unit for
liquid volume.
• The abbreviation for the liter is L.
• The graduated cylinder measures
liquid volume in milliliters (mL
(mL)).
• To measure the volume of liquid in a graduated
meniscus.
cylinder, you need to read from the bottom of the meniscus
• The meniscus is the curved surface at the top of a column of
liquid.
• The volume of water in the graduated cylinder is 53 mL.
mL
SI Base Units – Mass
• The mass of an object measures the amount of matter in
an object.
• The gram is the base unit for mass.
• The abbreviation for the gram is g.
• The instrument that is used to measure the mass of an
object is the triple beam balance.
balance
clip
• One gram is about the mass of one large paper clip.
• Weight is different from mass since weight is dependent
on the force of gravity.
Measuring Mass
• First, zero out the triple beam balance by moving the sliders to zero and
adjusting the knob until the two white lines meet on zero.
• Next, place the object on the center of the platform.
platform..
• Start with the middle beam (100s) and move the slider until the line on the
arm drops below zero line on the scale.
• Move the slider back one place and repeat the procedure for the top arm
(10s).
• Finally adjust the front slider (1s) until the line on the arm meets the zero
line on the scale.
Si Base Units - Temperature
• The physical property of temperature is related
to how hot or cold an object is.
• Temperature is measured in SI units with the
Kelvin scale.
• In classroom laboratories, the Fahrenheit and
Celsius temperature scales are often used.
• The instrument that is used to measure the
temperature of an object is the thermometer
thermometer.
Si Base Units - Time
• Time is the interval between two events.
• Time is measured in hours and seconds.
seconds
• The instrument used to measure time is
the stop watch.
watch
Summary of SI base units
Measurement
Unit
Symbol
Instrument/
Tool
Length
Meter
M
Solid
Volume
Liquid
Volume
Mass
Cubic
Centimeter
cm3
Meter Stick
or Ruler
Meter Stick
or Ruler
Liter
L
Gram
g
Temperature
Degrees
Celsius
Hours and
Seconds
°C
Graduated
Cylinder
Triple Beam
Balance
Thermometer
Hr or Sec
Stop Watch
Time
US vs. Metric Conversions
One Meter = 3.28 feet
One Pound = 454 grams
One Liter = 1.06 quarts
One Degree Celsius = 33.8o Fahrenheit