1. 1.3 Notes Derived Units

2. Derived Units
Derived units—cannot be measured with one SI base unit…it is a combination of units
Speed: m/s or meters/second
Volume of a cube: (L x w x h = )m3 or cm3
Density: g/cm3

3. Mass vs. Density
Which weighs more a pound of lead or a pound of feathers?
They are the same….1 pound!
Which would have a greater volume, a pound of lead or a pound of feathers?
A pound of feathers would take up more space.
Which has a greater density, lead or feathers? Which has its molecules more closely compacted?
Lead has smaller volume for same mass.

4. Density Density—the ratio of mass to volume.
Mass—the amount of matter that comprises an object;
measured in grams.
Volume—the amount of space that a piece of matter occupies;
measured in liters (l), milliliters (ml), cubic centimeters (cm3)
Different units for solids vs. liquids vs. gases
Formula for density: d = m/v
Density CANNOT be directly measured…must be calculated

5. More on Density
High density objects have a large mass compacted into a small space.
For example:
Low density objects have a small mass spread over a large space.

6. Why??