Physics Section 1.2 The system of measurement used in science is the SI system. (Système International d'Unites) SI Standards Quantity Unit Symbol length meter m mass kilogram kg time second s A derived unit is a combination of the seven fundamental units. m/s kg∙ m/s

The metric system is a system of prefixes used to indicate powers of a base unit. Prefix symbol power exa E peta P tera T giga G 10 9 mega M 10 6 kilo K 10 3 hector h 10 2 deka da 10 1 base unit deci d centi c milli m micro µ nano n pico p femto f atto a

Convert 3 g = _____mg.17 km = _____cm 2.5 ms = _____ks 2000 cm = _____Mm 100,000 ns = _____Ts 15 m 2 = _____cm 2.5 hm 2 = _____ µm 2 7 mm 3 = _____dam 3

Sources of Uncertainty of a Measurement 1.Method Error – using different techniques to obtain a measurement. 2.Instrument Error- using faulty or inappropriate equipment Ways to express the uncertainty of a measurement 1. accuracy 2. precision 3. significant figures Accuracy is a description of how close a measurement is to the accepted value. Precision is a description of the agreement among several measurements of the same quantity. Significant figures are those digits in a measurement that are known with certainty, plus one uncertain digit.

What is the length of the black rectangle?

Rules for Significant Digits 1. All nonzero digits are significant. 2. Zeros between significant digits are significant. 3. Zeros at the end of a number and right of a decimal are significant. 4. Zeros in front of a nonzero digit are not significant. 5. Zeros at the end of a number and left of a decimal are not significant unless indicated to be so.

How many significant figures are there in each number? 23,

Rules for Calculations with Significant Digits 1. Multiplication / Division: the final answer has the same number of significant digits as the measurement having the fewest significant digits. 2. Addition / Subtraction: The final answer can not be more precise than the least precise term.(Round to the appropriate decimal point)

Simplify (345 cm)(56 cm) (200 cm)(150 cm)(123 cm) 125 g 12cm m m cm cm

Rule for Rounding 1. Round down when the digit following the last significant digit is less than five. 2. Round up when the digit following the last significant digit is more than five. 3. If the digit following the last significant digit is a five: a. round up if the last significant digit is odd. b. round down if the last significant digit is even.

Round to the indicated value tenth hundredth 4.15 tenth 4.25 tenth 850 hundred

Assignment Page 20 Problems 1 - 4