Physical Quantities

1
Physical Quantities

• A quantity is a "physical quantity" if
• it expresses the result of a measurement,
• OR
• it expresses the result of a calculation using
  other physical quantities,
• OR
• (especially in learning situations) it is
  presented AS IF it were 1 or 2.

2
Physical Quantities

• Communicating the value of a physical quantity
  requires giving
• a number
• AND
• a unit
• AND
• an indication of accuracy

3
Accuracy

• Accuracy can be indicated by
• 1. words such as "about", "nearly", etc., when
  the accuracy is not great.
• 2. /- notations. (This should be the usual
  format in laboratory work.)
• 3. Significant digits