measurement & uncertainty. fundamental quantitysi system english system mass kilogram (kg) oz,...
TRANSCRIPT
Measurement & Uncertainty
FUNDAMENTAL QUANTITYSI SYSTEM ENGLISH SYSTEM• Mass kilogram (kg) oz, lb, ton
• Distance meter (m) in, ft, yd, mi
• Temperature Kelvin (K) °F
• Time second (s or sec) sec, min, hr, day
• Amount mole (mol)
DERIVED QUANTITY (derived from the fundamental quantities above)• Area (distance)2 m2 in2, ft2
• Volume (distance)3 m3, L in3, yd3
• Velocity (distance/time) m/s mi/hr
• Density (mass/volume) g/L lb/in3
*See table 1.5 for metric prefixes! (Know Pico through Mega)
Temperature Scales
• Celsius to Kelvin conversion:TK = T°C + 273
• Kelvin to Celsius conversion:T°C = TK - 273
• Fahrenheit to Celsius conversion:T°C = (T°F - 32) ÷ 1.8
• Celsius to Fahrenheit conversion:T°F = (1.8 • T°C) + 32
Accuracy & Precision
Accuracy - how close the measurement is to the “true” value
Precision – how close individual measurements are to each other.
Accuracy
PERCENTAGE ERROR (PE)
observed value - accepted (true) value
= --------------------------------------- X 100%
accepted (true) value
How many significant digits are there?
1.4563 cm0.00123 m1.0058 sec1.54 x 1015m
8.500 mm5003 km100. L
5000 mL
Addition & Subtraction
cm 6.4
cm 012.0
cm 42.5
mL 6450
mL 85063
10.0 cm
78610 mL
Multiplying & Dividing
mm 00012.0 x 26400.5
sec125.2
2.4500 m
.00063 m2
2118 m/s
Dimensional AnalysisA problem solving method using a series of multiplications
and divisions
Multiply by fractions called “conversion factors”ALL conversion factors are equal to 1There is a table of conversion factors in the back cover of
your textbook
STEPS OF DIMENSIONAL ANALYSIS1) put the given AND the given unit on the left2) arrange conversion factors (fractions) to cancel ALL units
EXCEPT the required unit
For fractional units (m/sec)– work one unit at a time
For units to powers (m3) – take the ENTIRE conversion factor to that power