1. Significant digits, base, and derived units CMA High school

2. Base units of the metric system Base quantityBase unitsymbol Lengthmeterm masskilogramkg Timeseconds TemperaturekelvinK Amount of a substance molemol Electric currentampereA Luminous intensity candelacd

3. Derived units Derived units are combinations of base units. Examples: speed= m/s Density = kg/m 3 Momentum = kg m/s Force = kg m/s 2 = Newton

4. Significant digit rules Nonzero digits are always significant All final zeros after the decimal point are significant Zeros between two significant digits are significant Zeros used solely as placeholders are not significant

5. Examples: 305940 = 5 sig digs 3.5000 = 5 sig digs 0.0000000000500 = 3 sig digs 4.002 = 4 sig digs 0.000000002 = 1 sig dig 120000000000 = 2 sig digs

6. Adding and subtracting sig digs Line up numbers with the decimal to add or subtract, then round the answer to the smallest number of significant digits after the decimal that you started with. 24.686m + 2.343m + 3.21 m = 30.239 m Round the answer to 30.24 m

7. Multiplying and dividing sig digs After multiplying or dividing, round your answer up to the smallest total number of significant digits that you started with. ( Don’t pay attention to the decimal) 3.22 cm x 2.1 cm = 6.762 cm 2, round up to 6.8 cm 4596/ 1 = 4596, round your answer to 5000

8. Homework/ classwork http://lectureonline.cl.msu.edu/~mmp/appli st/sigfig/sig.htmhttp://lectureonline.cl.msu.edu/~mmp/appli st/sigfig/sig.htm