Presentation on theme: "QuantityEnglish unitabbSI unitabbDefinition mass Pounds ounces lbs ozgramg amount of matter in an object volume Gallon quart gal qtliterL amount of space."— Presentation transcript:
QuantityEnglish unitabbSI unitabbDefinition mass Pounds ounces lbs ozgramg amount of matter in an object volume Gallon quart gal qtliterL amount of space an object occupies length Inches, feet Yards, miles in ft yd mimeterm distance between two objects timeseconds Hr S minSecondssfinite duration temperatureFahrenheitºF Kelvin Celsius K ºC how hot or cold something is amount of substanceN/A molemol the amount of a substance
KingHenryDiedByBydrinkingchocolatemilk KiloHectaDecabasedecicentimilli ^310^210^110^010^-110^-210^-3 MEGA 10 6 M micro10 -6 μ GIGA 10 9 G nano10 -9 n TERA T pico p
kg = _________g cm = _________m mL = _________L 4. 25mg = _________g cm = ______mm mL = _________L g = _________kg mm = _______m m = ____mm kg = _______mg
Accuracy- How close a measured value agrees w/ the correct value Precision-How close ea. Measurement agrees w/ ea. other
Which of the measuring devices would provide a more accurate measurement? Why is this one a better device to use for measuring? Sec 2-3 Pg 44-57
1. Exact Numbers: may be counted or defined. 1. Are absolutely accurate 2. People in a room. 2. There is some uncertainty in measurements. 3. Sig. Figs. Indicate the uncertainty in the measurements. 1. Digits believed to be correct by those that makes them 2. Can only report ONE estimated digit.
Using a calibrated instrument of measure you can be certain of the accuracy of some of the digits measured. Using a calibrated instrument of measure you can be certain of the accuracy of some of the digits measured. − The last digit of the measurement is however, always questionable Excluding the last digit would be misleading Excluding the last digit would be misleading − With the last digit you have some indication of the value’s likely range Any measurement reported should consist of the certain digits plus the uncertain digit. Any measurement reported should consist of the certain digits plus the uncertain digit. − The last digit is uncertain, but it isn’t insignificant…
Sec 2-3 Pg 44-57
Since only the significant digits are reported it is important to be able to determine all the significant digits in a measurement. Since only the significant digits are reported it is important to be able to determine all the significant digits in a measurement. − There are a set of rules that allow us to determine the significance of any figures in any measurement even if we don’t know the origin of the measurement
1. Zeros (0) used only to position the decimal are not significant 3 sig figs depends on the measurement
2. In x/÷, an answer contains no more sig figs than the least # of sig figs used in the operation. 1. ie: (12.34 cm)*(1.23 cm) = cm 2 Correct answer =15.2 cm 2
1. In +/- the last digit retained in the answer is determined by the position of the first estimated number. 2. In other words 1. ( )=47.54 ( )= 6.64
Sec 2-3 Only measurements are given significance. Only measurements are given significance. − There are some numbers that aren’t considered in terms of significance. o Conversion factors have an infinite number of significant figures (ratios of equal measures, like 1 ft/12 in or 60 sec/1 min) o Exact numbers also have an infinite number of significant figures, like 20 apples or 10 test tubes
9.0 km How many significant figures does each of the following measurements have? How many significant figures does each of the following measurements have? g btu sec amps kg 6
Pg Sec 2-3 Just because the calculated answer in your calculator has 8 digits in the answer – doesn’t mean they are all significant Just because the calculated answer in your calculator has 8 digits in the answer – doesn’t mean they are all significant − Answers calculated from measurements may not be expressed with more significant digits than any of the original measure- ments − Calculator answers must be rounded to reflect the least accurate measurement
1. Calculate the area of a crystal surface that measures 1.34 m by m. 2. Calculate how many minutes a project took if the times spent on it each day were 92.5 min, min, 25.0 min, 45 min, and min. 3. Calculate how many hours the result from #2 would work out to be. Carry out each of the mathematical operation. Carry out each of the mathematical operation m, 291 min, 4.85 hrs
1. 32,700 Write the following #’s in sci notation… Write the following #’s in sci notation… 3.27 x ,024, x x 10 -3
Pg Sec nd function button you push before the EE button The EE button is 2 nd function of the comma button Avoid this button like the plague E 4/1.2 E Use this button to enter a negative number █
1. Units that are made up of 2+ basic units, ie. Velocity, force, acceleration. 1. Density 1.Amount of mass per unit volume. 2.D=m/v 3.Unites are g/cm 3 or g/mL or g/L 4.Cm 3 is a unit of volume for solids because v=l*w*h cm*cm*cm=cm 3 2. Example: A mL sample of ethanol has a mass of 37.32g. What is its density? (hint: denisty= mass/volume)
Specific Gravity › Ratio of a substance’s density to the density of H 2 O › Density of H 2 degrees CH 2 › No units
1. Read problems 2. Write formula 3. Write variables 4. Plug in numbers 5. Solve 1. For example: Express the density of mercury in lb/ft 3 if the density if g/cm 3.
A block of Zinc metal has the dimensions 5.0 cm X 7.0 cm X 20.0 cm, and its mass is 5.0 kg. What is the density of the Zinc metal in g/mL? Zinc’s density is 7.13 g/cm 3, what is the percent error from the lab? A block of Zinc metal has the dimensions 5.0 cm X 7.0 cm X 20.0 cm, and its mass is 5.0 kg. What is the density of the Zinc metal in g/mL? Zinc’s density is 7.13 g/cm 3, what is the percent error from the lab?
Also called the factor label method Easy way to convert between English and SI (metric). Uses equivalent amounts › 12 in = 1 ft = 12in/1ft › 38m=______________ft.
English to Metric Conversions length 2.54cm=1in 39.37in=1m 1.609km=1mi volume 1L=1.057qt 28.32L=1cubic foot mass 453.6g=1lb 1g= oz 1 metric ton=1.102 standard tonnes
1. 29in or 2.9*10 1 in tsp 3. 1*10 2 lbs *10 1 mi *10 -1 gal *10 4 oz *10 2 yds 8. Example 2: 8.484*10 2 lbs/ft 3
%Error = (Actual-Theoretical) ___________________ * 100 Theoretical Will be Θ if the accepted value is greater. (+) if the accepted value is less.
Express 12gal in cm 3. Suppose Mrs. Fraga’s Bentley contains a gas tank (handmade) that holds up to 16 gal of fuel. The price of gas is $0.315 per Liter (obviously not a problem). How much would Mrs. Fraga need to charge on her AmEx Platinum for one full tank of gas? Does not include tip.