topic: measurement aim:: what is mass and how is it measured? do now: explain the difference between...
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TOPIC: MeasurementAim:: What is mass and how is it measured?
Do Now: Explain the difference between volume and mass.
HW: Create 20 Density problems
•Box A has a greater density than Box B
•Why? Because it has a greater mass (more matter/ molecules)
A B
Which box has a greater density?
Example #1: What is the density of a metal block that has a mass of 525g and the volume of each half is 50cm3?
Example #2: The metal block was split in half. The mass of each half is 262.5g and the volume of each half is 25cm3. Calculate the density.
M = 20 gm V = 10 mLDensity = 20/10 = 2 gm/mL
Cut the block in half
M = 10 gm V = 5 mLDensity = 10/5 =
2gm/mL
•*Each pure substance has it’s own density no matter what size it is.*
The density of water is ALWAYS 1g/cm3!!!!
Why will an object float or sink?
•FLOATS when the density of the object is LESS than the density of the liquid.
•SINKS when the density of the object is GREATER than the density of the liquid.
Less dense than water
More dense than water
• http://ippex.pppl.gov/interactive/matter/denslab.html
Notice the empty spaces within the ice structure, as this translates to a more open or expanded structure. The ice
structure takes up more volume than the liquid water molecules, hence ice is less dense than liquid water.
Topic: Measurement
Aim: To practice measuring volume.
Do Now: Explain why some objects float while others sink.
HW: Ditto – Volume & Density
(Finish Volume Activity)
Let’s summarize…
1. What is the equation for determining density?
2. What do you know about the density of different substances?
3. What is the density of water?
4. What would happen to the density of a substance if it was cut into four pieces?
5. Why do substances float in water?
6. Why do substances sink in water?
Review:1. The units of density could bea. milliliters per gram b. milliliters c. gram d. grams per milliliter
2. What is the density of a 40-gram object with a volume of 20 milliliters?
a. 2 g b. 2 ml/g c. 2 g/ml d. 2 ml/g
3. A cube is 1 cm on each side and has a mass of 2 grams. Will it float?
a. yes
b. no
c. The only way to tell is to put it in water.
4. The density of water is
a. 1 mL/g.
b. 1 g/L.
c. 1 g/mL.
d. 1 kg/mL.
5. An object that floats in water has a density of
A) less than 1 g/mL. B) equal to 1 g/mL.
C) greater than 1 g/mL. D) equal to 10 g/mL.