Measurements and Units

Chapter One- Let's Measure and Convert!

Chapter Quiz

Chapter Video

Units of Measurement

What is a measurement? Size, length, or the amount of something. You have measured your foot at a shoe store? Or your weight on a scale at the doctors? Or maybe your age which is measured by the calendar! So then what is a unit? A unit is simply what you say after the number. Such as my shoe size is 9 inches, inches is the unit. My weight is 125 pounds, pounds is the unit. I am 21 years old, the unit is years. For physics we ALL use S.I. units.

Common SI Units (Always use these in Physic Problems!):

• Distance or Length--- meters (m)

• Mass--- kilograms (kg)

• Time--- seconds (s)

• Temperature--- kelvin (K)

• Electric Current--- amperes (A)

• Energy and Work --- joule (J)

• Force--- Newton (N)

• Power--- Watt (W)

You will learn when these are used later but always use these units. Sometimes you will be given different units REMEMBER you have to convert into these units before plugging into the equations!

Unit Conversions

Lets get comfortable converting with units you already know about.

giga(G)= 10^9

mega (M)= 10^6

kilo (k)= 10^3

centi (c)= 10^-2

milli (ml)= 10^-3

micro (µ)= 10^-6

nano (n)= 10^-9

pico (p)= 10^-12

Lets say you have 100 cm, you need this to be in meters! So 100 cm multiply this by 10^-2 since centi=10^-2..... you will get 1 meter! The negative 2 tells you to move the decimal place to the left two times. 100.0 cm--- 1.00 m.

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