PHYSICS BASICS

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PHYSICS BASICS

• Science Measurements and Units

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MEASUREMENTS

• Measurements consist of a number and a unit.

• Example

100 meters
the number of units
the unit
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INTERNATIONAL SYSTEM OF UNITS (SI units)

• Developed for the sake of
• Consistency (minimize errors)
• Clarity (ease of understanding)
• Communication (sharing data)

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BASE SI UNITS (standard units)
Measured quantity
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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
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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

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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?

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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?
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ACCURACY

• Accuracy is the extent to which a measurement
  approaches the true value.

Actual Time 210 pm
Your Time 205 pm
Your accuracy is off by 5 minutes
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- The bulls 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
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PRECISION

• Precision is the degree of exactness of a
  measurement.

• Based on the scale of the measuring instrument.

Smallest tick marks represent millimeters (mm)
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PRECISION VS. ACCURACY
A
B
C
D

• AGood precision and accuracy
• BSome accuracy and poor precision

• CGood precision and poor accuracy
• DPoor precision and accuracy

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Discussion Question

• When shooting free throws, is it better to be
  precise or accurate?

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• Its better to be accurate.