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Work sheet (1) Chapter (1) Subject Name Date Grade 9 Cluster SI Units ASP I-Choose the best answer: 1. What two dimensions, in addition to mass, are commonly used by physicists to derive additional measurements? A. B. C. D. length and width length and time area and mass velocity and time 2. The symbol mm represents a A. B. C. D. micrometer megameter millimeter manometer 3. The SI base unit used to measure mass is : A. liter B. meter C. kilogram Page 1 of 5 second D. 4. The SI base unit for time is A. 1 day B. 1 minute C. 1 hour D. 1 second 5. The most appropriate SI unit for measuring the length of an automobile is the A. micrometer B. meter C. kilometer D. nanometer 6. The radius of Earth is 6 370 000 m. Express this measurement in km in scientific notation with the correct number of significant digits. A. B. km km C. km D. km Page 2 of 5 7. A lack of precision in scientific measurements typically arises from A. limitations of the measuring instrument. B. human error. C. lack of calibration. D. too many significant figures 8. How does a scientist reduce the frequency of human error and minimize a lack of accuracy? A. Take repeated measurements. B. Use the same method of measurement. C. Maintain instruments in good working order. D. all of the above 9. Three values were obtained for the mass of a metal bar: 8.83 g; 8.84 g; 8.82 g. The known mass is 10.68 g. The values are A. accurate. B. both accurate and precise. C. precise. D. neither accurate nor precise. 10. Calculate the following, and express the answer in scientific notation with the correct number of significant figures: 21.4 + 15 + 17.17 + 4.003 A. B. C. D. II- solve the following questions 11- Convert 15km to meters using scientific notation. Page 3 of 5 12. Convert g to kilograms using scientific notation. 13. Convert m to millimeters using scientific notation. 14. How many significant figures does 0.050 200 mg have? 15. How many significant digits does 40.60 have? 16. Convert the speed shown in the figure to km/h . Page 4 of 5 III- Answer the following question(s): 17. How can only seven basic units serve to express almost any measured quantity? 18. How can method error be minimized? 19. Distinguish between precision and accuracy. 20. What two base quantities are used to measure speed? 21. What is unique about the value of a conversion factor? Why is this value important? Page 5 of 5