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PHYSICS BASICS. Science Measurements and Units. Measurements consist of a number and a unit. Example. MEASUREMENTS. 100 meters. the number of units. the unit. INTERNATIONAL SYSTEM OF UNITS (SI units). Developed for the sake of Consistency (minimize errors)
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PHYSICS BASICS Science Measurements and Units
Measurements consist of a number and a unit. Example MEASUREMENTS 100 meters the number of units the unit
INTERNATIONAL SYSTEM OF UNITS (SI units) • Developed for the sake of • Consistency (minimize errors) • Clarity (ease of understanding) • Communication (sharing data)
BASE SI UNITS (standard units) Measured quantity
DERIVED UNITS • Derived Units: Combinations of the 7 base units. • Examples • Area (length x width) m x m = m2 • Velocity (distance/time) = m/s 50 m2 5 meters 10 meters
How to Measure? • Know how to operate the measuring instrument • Which unit(s) is represented? • What does each tick mark represent? • Are there multiple scales? • Did you zero out the instrument (if possible) • Be skilled and patient enough to measure with the greatest detail possible
What do the tick marks represent on a meter stick? • What unit is represented by the smallest tick mark on the meter stick? m? dm? cm? mm? *
What do the tick marks represent on a meter stick? • What is the measurement? In mm? 65 mm In cm? 6.5 cm In dm? .65 dm In m? 0.065 m?
Accuracy is the extent to which a measurement approaches the true value. ACCURACY Actual Time: 2:10 pm Your Time: 2:05 pm Your accuracy is off by 5 minutes
- The bull’s eye represents the true value.- The darts represent three separate measurements these darts show good accuracy accurate which paint ball mark is more accurate? less accurate
Precision is the degree of exactness of a measurement. Based on the scale of the measuring instrument. PRECISION Smallest tick marks represent millimeters (mm)
A—Good precision and accuracy B—Some accuracy and poor precision C—Good precision and poor accuracy D—Poor precision and accuracy PRECISION VS. ACCURACY A B C D
Discussion Question • When shooting free throws, is it better to be precise or accurate?