What are the measurements of the metric system
Kilo
Hecto
Deka
Base
deci
centi
milli
king henry slider
king - kilo (k)
henry - hecto (h)
died - deka (D)
by - Base
drinking - deci (d)
chocolate - centi (c)
milk - mili (m)
What are the basic unit for length, mass and volume
Length - meters (m)
Mass - grams (g)
Volume - Liters (L)
Precision
How close a series of measurement are to one another
Accuracy
How close a measurements comes to and actual or true value
How can we make both accurate and precise measurements
- Be careful and don’t rush
- REPEAT
- Always estimate one extra digit for every measurement
Significant Figures
- The number of digits thought to be correct by the person doing the measuring
- Include all digits that can be read directly from the measuring device plus one estimated digit
What are the rules for counting sig figs
- Leading zeros are never significant
- Zeros within a non zero digit are always significant
- Zeros that show only where the decimal point falls are not significant
- Trailing zeros that are not needed to show where the decimal point falls are significant
Rules for rounding sig figs
- If the digit to be rounded is less than 5 then round down
- If the digit to be rounded is more that 5 then round up
Sig figs with Addition and subtraction
The answer should be rounded to the same number of decimal places as the measurement with the least number of decimal points
Sig figs with multiplication and division
The answer should be rounded to the same number of sig figs as the measurement with the least number of sig figs
Error
The difference between the experimental value and the accepted value
When are zeros significant
- when the zero is between non zero digits
- At the end of a number that includes a decimal point
When are zeros not significant
- Before the first non zero digit
- At the end of the number WITHOUT a decimal
Why are sig figs important
To make sure the answer you get is not more precise than the numbers you started with
Equivalency
Two different units that describe the same amount
Conversion factor
A fraction made from an equivalency
Steps for using dimensional analysis
- Identify the given and needed units
- Write the given unit as a numerator (over 1)
- Write equivalencies and conversion factors for the two units (given and needed)
- Write the conversion factors so that the given units are cancelled and the needed units remain (may need to be done in multiple steps)
- Multiply across the top and bottom - solve
Density
The amount of stuff (mass) occupying a certain amount of space (volume)
Equation for density
Density = mass / volume
Equation for mass
M = D x V
Equation for volume
V = M / D
