Momentum Solve these problems: (33 x 10 6 ) + (3 x 10 4 ) (4000 x 10 -2 ) – (3 x 10 3 )
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Transcript of Momentum Solve these problems: (33 x 10 6 ) + (3 x 10 4 ) (4000 x 10 -2 ) – (3 x 10 3 )
Momentum
Solve these problems:
(33 x 106) + (3 x 104)
(4000 x 10-2) – (3 x 103)
Solve these problems:
(33 x 106) + (3 x 104)
Momentum
Solve these problems:
(33 x 106) + (3 x 104)
(3300 x 104) + (3 x 104)
Momentum
Solve these problems:
(3300 x 104) + (3 x 104)
3303 x 104
Momentum
Solve these problems:
(3300 x 104) + (3 x 104)
3303 x 104
3.303 x 107
Momentum
Solve these problems:
(4000 x 10-2) – (3 x 103)
Momentum
Solve these problems:
(4000 x 10-2) – (3 x 103)
(4000 x 10-2) – (300000 x 10-2)
Momentum
Solve these problems:
(4000 x 10-2) – (3 x 103)
(4000 x 10-2) – (300000 x 10-2)
-296000 x 10-2
Momentum
Solve these problems:
(4000 x 10-2) – (3 x 103)
(4000 x 10-2) – (300000 x 10-2)
-296000 x 10-2
-2.96 x 103
Momentum
5 Bonus Points(next week – 1 pt off everyday)Lab Fee, Safety Contract,
Notebook Set-up & Extra Item
Significant FiguresChap 1 pg.17
• Experimental work always has error!• Because of this it is important to minimize
error as much as possible when taking measurements
• Key Point #1 Accuracy is how close a measured value is to the true value
Accuracy Issues!
• Accuracy problems are always due to error– Method error – when measurements are
taken using two different methods• Ex. Reading a meniscus from different angles
– Instrument error – when measurements are taken using instrument that does not work correctly
• Ex. Balance is not calibrated or zeroed; worn down metersticks
• Key Point #2: Precision describes how exact a measurement can be. Typically due to limitations on the measuring instrument
Precision
• 1.345m is more precise than 1.3m– Ex. If meterstick is only divided into cm it will
be difficult to measure something a few mm thick
• A precise series of measurements will have values close to each other– 12.34kL; 12.35kL; 12.33kL = Precise– 12.343ng; 12.901ng; 22.392ng = NOT Precise
• Key Point #3: You can keep track of the precision of a measurement by using significant figures (sigfigs);
Significant Figures
-When you measure, Sig Figs are all the numbers you actually measure plus one estimated digit
-Ex. Measure this line with two different rulers…
Significant Figures-132.75g- 5 sigfigs- Actual measurement between 132.745g and 132.755g
Significant Figures
Significant Figures
Measurement Activity
Everyone should have rulers A, B & C…as well as
distance 1 & 2.
Significant Figures
Distance 1:Ruler A:Ruler B:Ruler C:
Significant Figures
Significant Figures
Distance 2:Ruler A:Ruler B:Ruler C:
Significant Figures
Key Point #4: There are 4 rules to counting sigfigs in
measurements!
Significant Figures
Significant Figures Rules#1 – All non-zero digits are significant!
Significant Figures
Significant Figures Rules
3462m
0031300kL
Significant Figures
Significant Figures Rules#2 – Zero Sandwich – zeroes between two non-zero digits are significant.(Ex. – 90003 has 5 sig figs)
Significant Figures
Significant Figures Rules
34062ms
00310300Gb
Significant Figures
Significant Figures Rules#3 – zeros at the end of a number and also to the right of the decimal are significant
Significant Figures
Significant Figures Rules
36200cW
03.130mHz
Significant Figures
Significant Figures Rules
306.200ph
0201500Ts
Significant Figures
Significant Figures Rules#4 – NO MATTER WHAT … zeroes to the left (of numbers) never count!!!
Significant Figures
0.0200ms100000000000000kJ
2028m
Significant Figures
100400g1.040kW9902.mW
Accuracy, Precision
• Is it possible for a set of data to be precise but not accurate? Explain.
Significant Figures
203.00000000.3
77.00
IP
The following students measure the density of a piece of lead three times. The density of lead is actually 11.34 g/cm3. Considering all of the results, which person’s results were accurate? Which were precise? Were any both accurate and precise?
a. Rachel: 11.32 g/cm3. 11.35 g/cm3. 11.33 g/cm3b. Daniel: 11.43 g/cm3, 11.33 g/cm3, 11.42 g/cm3c. Leah: 11.55 g/cm3, 11.34 g/cm3, 11.04 g/cm3
Exit TicketHow many significant digits in the following measurements?
702.0m.00340kL20700m
Organize the following measurements from the least accurate instrument to the most accurate.
98.020m 90m 18.23m