VARIOUS NOTES: 'DENSITY and MEASUREMENT'

**Measurement Notes **IF HIGHLIGHTED, VERY IMPORTANT!**

__PLEASE MAKE NOTE CARDS FROM THE HIGHLIGHTED YELLOW TERMS:__

** Estimation-** Helps you make a rough measurement of an object.

** Precision-** A description of how close measurements are to each other

** Accuracy-** When you compare a measurement to the real, actual, or accepted value.

** SI-**International System that allows people all over the world to use the same base for measurements.

** Meter-** the SI base for measuring length. (distance)

** Volume-** The amount of space an object takes up.

** Mass-** The measurement of the amount of matter in an object.

** Gram-** The SI base for measuring mass.

** Weight-** The measurement of force (gravity)

** Rate-**The amount of change in one measurement over a period of time

** Liters-** The SI base for volume.(liquid)

** Centimeter Cubed or CM^{3} -** SI base for volume (solid)

** Density-** A measure of how much mass is continued in a given space

** **

I.**What do we measure?**

**A.** **Distance - length, width, height**

**B.** **Temperature**

**C.** **Volume**

**D.** **Mass - related to weight but not the same**

**E.** **Time**

**F.** **Speed - distance per time - a CALCULATED UNIT**

**G.** **Density - mass per volume - a CALCULATED UNIT**

**II. DISTANCE or LENGTH – the amount of space between 2**

**objects**

**A.** **What do we measure distance or length with?**

**1.** **Meter stick**

**2.** **Ruler**

**3.** **Tape measure**

**B. What units do we use to measure distance?**

**1.** **Standard or Customary**

**a.** **Inches, feet, yards, miles**

**b.** **12 inches = 1 foot, 3 feet = 1 yard, 5280 feet = 1 mile**

**2.** **Metric System - Meter - basic unit of distance - little**

**more than 3 feet**

**a.** **Deci (d) means .1 of something so a decimeter**

**is .1 of a meter or 10 decimeters equals 1 meter.**

**b. Centi(c) means .01 of something so a**

**centimeter is .01 of a meter or 100 centimeters equals 1 meter**

**c. Milli(m) means .001 of something so a**

**millimeter is .001 of a meter or 1000 millimeters equals 1 meter.**

**d.** **Deka (da) means 10 of something so a**

**dekameter is 10 meters.**

**e. Hecto(h) means 100 of something so a**

**hectometer is 100 meters.**

**f. Kilo (k) means 1,000 of something so a**

**kilometer is 1,000 meters.**

***** Metric system is based on a series of 1 to 10**

**relationships. One of them is that 10 millimeters equals 1 centimeter.**

**III.** **Volume – how much space an object takes up.**

**A.** **What do we measure with?**

**1.** **Graduated cylinder**

**2.** **Beaker**

**3.** **Displaced volume – water usually**

**4.** **Calculate using dimensions – formula for a box is**

**volume = length * height * width or V=l*w*h**

**B.** **What units are used to measure volume?**

**1.** **Standard or customary are gallons, cups, pints, etc**

**2.** **Metric unit is the Liter – basic unit of volume in**

**metric system**

**a.** **In science we mainly use milliliters or mL.**

**b.** **The whole unit is based on the amount of**

**water that has a mass of 1 gram – this is how much a milliliter or mL is.**

**c.** **There are 1000 mLs in a liter or 2000 of them in**

**a 2 liter bottle of Pepsi.**

**d.** **Graduated cylinders and beakers are marked**

**off in milliliters.**

**IV.** **Mass – how much matter is in an object.**

**A.** **What do we measure with?**

**1.** **The balance scale – triple beam balance in this class.**

**B.** **What units are used?**

**1.** **The standard unit of pound does not measure mass**

**but rather weight – these might be the same on Earth but weight depends upon gravity so it changes if gravity changes, like in space.**

**2.** **Metric unit mass is the Gram.**

**3.** **We do most of our measurements in grams – down**

**to the nearest tenth of a gram – this is how accurate the balance scales are.**

**V.** **Temperature – the amount of thermal energy in an object or**

**substance.**

**A.** **What do we measure with?**

**1.** **A thermometer – usually a metal backed**

**thermometer that uses colored water.**

**2.** **Can use large dial thermometers or long glass**

**thermometers.**

**B.** **What units are used?**

**1.** **The standard unit is Fahrenheit. We will not use**

**this unit in class but you should know that water freezes at 32 degrees and boils at 212 degrees. These are hard numbers to remember or work with – this is why the Fahrenheit system is not as good as the metric.**

**2.** **The metric unit is Celsius.**

**a.** **This unit is based on the properties of water –**

**just like volume and mass. The base line for Celsius is the freezing point of water – 0 degrees Celsius. The boiling point of water is 100 degrees Celsius.**

**VI.** **Time – we will use stopwatches to measure the passing of time – we will**

**measure it in terms of seconds and hundredths of a second.**

**VII.** **Speed – a calculated unit that determines how far an object**

**goes in a certain period of time.**

**A.** **A calculated measurement is one that you do not**

**measure directly but have to use a formula to determine**

**B.** **The formula for speed is distance divided by time**

**C.** **The units for speed are a combination of a distance and**

**time - for example – 32 meters per second or 65 miles**

**per hour**

**VIII.** **Density – a calculated measurement that determines an**

**objects mass for a certain amount of volume.**

**A.** **To calculate density you must use the following**

**formula – mass divided by volume = density.**

**B.** **The units for density are a combination of a mass**

**unit and a volume unit. The most common density unit is grams per milliliter (g/mL).**

**C.** **We determine density by using a balance scale and**

**a graduated cylinder and then dividing the measurements.**

**D. The great thing about density is that it does not**

**depend on the size of an object – all pieces of gold, no matter how big or small, have the same exact density.**

**E.** **This makes density useful in determining what an**

**object is made of – if you know the density, you can compare it to known densities and figure out what its made of.**

Posted: Wednesday, July 23, 2014