Chapter 1 Unit 1a

1. Physics tools! Chapter 1 Unit 1a

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3. Essential Questions • What is Physics? • Why do scientists use the metric system, instead of the English or some other system?

5. Now, you measure the length and width of your table only using your hands and or feet or some other means. • Write down your results so we can go over them as a class. • Compare your results with the grop next to you. • How difficult is it to compare your results with all of these different unit systems?

6. Topics in Physics The study of motion and what causes motion. Mechanics: The study of heat and temperature. Thermodynamics: The study of specific types respective motions. Waves and Vibrations: The study of electricity, magnetism and light. Electromagnetism: Relativity: The study of particles moving at any speed. The study of the behavior of submicroscopic particles. Quantum mechanics:

7. Scientific Method 1. Make observations and collect data that lead to a question. 2. Formulate and objectively test hypotheses by experiments. Hypotheses: A reasonable explanation for observations – one that can be tested with additional experiments. 3. Interpret results, and revise the hypothesis if necessary. 4. State a conclusions in a form that can be evaluated by others. Controlled experiment: A experiment involving the manipulation of a single variable or factor.

8. SI Standard Units Length: meters ( m ) Time: seconds ( s ) Speed: meters per seconds ( m/s ) Acceleration: meters per second squared ( m/s2 ) Mass: Kilograms ( kg )

9. Prefix Abbreviation Value Tera T 1012 Giga G 109 Mega M 106 Kilo k 103 Hecto h 102 Deka da 101 Deci d 10-1 Centi c 10-2 Milli m 10-3 Micro µ 10-6 Nano n 10-9 Pico p 10-12 Femto f 10-15 Metric Multipliers

10. Length Conversions: 1 km = 1000 m = 100,000 cm = 1,000,000 mm 1 m = 0.001 km = 100 cm = 1000 mm 1 cm = 0.00001 km = 0.01 m = 10 mm 1 mm = 0.000001 km = 0.001 m = 0.1 cm Time Conversions: 1 year = 365 days = 8760 hr = 5.256 x 105 min 1 day = 24 hr = 1440 min = 8.64 x 104 s 1 hr = 60 min = 3600 s 1 min = 60 s Mass Conversions: 1 kg = 1000 gm = 1,000,000 mg 1 gm = 1000 mg = 0.001 kg 1 mg = 0.001 gm = 0.00001 k

11. Significant Figures 1. Zeros between other nonzero digits are significant. 50.3 m, has 3 significant digits. 2. Zeros in front of nonzero digits are not significant. 0.0008 ms, has one significant digit. • Zero that are at the end of a number and also to the • right of the decimal are significant. 57.00, has 4 significant digits. • Zeros at the end of a number but not to the left of a • decimal are significant. But we will not treat them as • significant. 20, has one significant digit.

12. Convert 75 km to cm. 75 km 1 cm = 7.5 x 106 cm 10-5 km 75 km 1000 m 100 cm = 7.5 x 106 cm 1 km 1 m

13. Convert 85 cm/min to m/s 85 cm 1 m 1 min = 1.4 x 10-2 m/s 60 s 102 cm min Convert 50g to kg. 50 g 1 kg = 0.05 kg 103 g

14. Convert 54 mm to m. 5.4 x 10-2 m or 0.054 m Convert 3.5 kg to g 3.5 x 103 g Convert 105 km/h to m/s 29.2 m/s

15. Dimensional Analysis ? vf and viare in m/s t in s a in m/s2 vf = vi + at OK

16. viin m/s t in s a in m/s2 d in m ? Will not work

17. ? vf = vi2 + 2ad NO ? d = vit + ½ at2 Yes

18. So, What is Physics?