1. Daily Science (Aug) 1. Convert 3.56 m into dm 2. Convert 113 lbs into g (438 g in 1 pound) 1. Convert 1.65 km into inches (1 in = 2.54 cm)

2. PG. 15 Density

3. Density is a ratio that compares the mass of an object to its volume. density= mass/volume d= m/v Units: g/cm 3 or g/mL

4. Calculating Density in a Lab Use water displacement method Record starting volume, place object in, record final volume Calculate mass Can also sometimes measure volume using a ruler

5. Practice Problems 1. Calculate the density of a rock that has a mass of 5.6 g if when placed in a graduated cylinder that started at 10 mL, rose to 13 mL. 2. Find the mass of a metal block that has a density of 8.7 g/mL and a volume of 2.1 cm 3. 3. Find the volume of a piece of aluminum wire that has a mass of 4 g and a density of 6.6 g/mL.

6. Percent Error Percent error is the ratio of an error to an accepted value. Percent error= {(actual value-experimental value)/actual value} x 100

7. PE practice problems You calculate the density of a piece of metal to be 3.4 g/mL. The actual density is 3.7 g/mL. Calculate the percent error.