9/8/2011

Post date: Sep 08, 2011 7:59:18 PM

    • Bell ringer (verbally) - why are some very heavy, metal objects (such as boats) able to float, but a tiny pebble will sink?

    • Density notes

      • Density = mass / volume

      • Mass

        • The amount of matter that makes up an object

        • Measured using a balance

        • Measured in grams (g)

      • Volume

        • The amount of space an object takes up

        • Measured using a graduated cylinder or by measuring dimensions and doing a calculation

        • Measured in milliliters (mL)

      • Density is measured in grams per milliliter (g/mL)

  • Density practice (to be turned in): Calculate the density of each of the following objects

      • 1. mass = 50 g, volume = 10 mL

      • 2. mass = 100 g, volume = 200 mL

      • 3. mass = 20 g, volume = 500 mL

      • 4. mass = 150 g, volume = 30 mL

      • 5. mass = 250 g, volume = 250 mL

    • Calculating Volume

      • For a cube, volume is found by multiplying length by width by height, or V = l*w*h

      • For a sphere, volume is found by multiplying 4/3 by pi by the cube of the radius, or V = (4/3)*pi*r^3, or approximately V = 4.18*r*r*r

      • For an irregularly shaped object, fill a beaker with water, note how high the water goes, then gently lower the object into the beaker. The water level will rise by an amount equal to the volume of the object. This is called the displacement method.

  • Density practice (add on to previous): calculate the density of each of the following objects

      • 6. A box with dimensions of 4 cm by 3 cm by 2 cm and with a mass of 20 grams.

      • 7. A sphere with a radius of 4 cm and a mass of 8 grams.