Physics 2 Robak
The Metric Ruler
Some rulers indicate the LARGEST NUMBERED value on the ruler
Some rulers indicate the MEASUREMENT SYSTEM on the ruler
Some rulers indicate the SMALLEST MARKED value on the ruler
Some rulers don’t indicate anything on the ruler
Rule #1 – KNOW THE RULER YOU ARE USING
Rule #2 – KNOW HOW BIG A m, dm, cm, mm ARE
Hints:
· a meter (m) is a little bigger than a yard
· a decimeter (dm) is about the width of your hand
· a centimeter (cm) is about the width of your finger
· a millimeter (mm) is about the thickness of your fingernail
Using a Metric Ruler WITH a VISIBLE 0 MARK
1. Set one end of the object at the zero point
2. Read the measurement at the other end of the object
· If the end of the object lands between two numbers use the lesser number
· Each mm is .1 cm so just count the number of mm lines from the last cm and put that after the decimal point
Example 1:
· Always read your measurement one place more than the precision of the ruler. This ruler has a precision of .1 cm so measure to the .10 cm at least.
Example 2:
Using a Metric Ruler WITHOUT a VISIBLE 0 MARK
Set one end of the object at a numbered mark that is visible such as the 1.0 cm or 1.00 dm mark
Read the measurement at the other end of the object
· If the end of the object lands between two numbers use the lesser number
· Each mm is .1 cm so just count the number of mm lines from the last cm and put that after the decimal point
· Subtract from your measurement the number the object was started at.
Example 1:
· Again always read your measurement one place more than the precision of the ruler. This ruler has a precision of .1 cm so measure to the .10 cm at least.
Example 2:
Estimating Digits While Measuring Objects
· If the measurement of an object does not end exactly on a mark you are allowed to estimate the next place value (one decimal place to the right) and consider it part of your measurement.
· This works with all measurements (distance, volume, & mass)
Example 1: The precision of most of our rulers is to the mm. What is our precision if we estimate one place past the mm? .01 cm
Measure the following block.
Example 2: What if the precision of our ruler was only to the cm. What is our precision if we estimate? .1 cm
Measure the following block.