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Date: 9-11-13Day Plan: Presentations
Scientific Notation Tomorrow
Density vs. Weight Pre-lab (lab tomorrow)
Opener: A. 0.002030 D. 0.004300 B. 1.005 E. 1000.1 C. 0.00860 F. 230.1 + 2.4234
G. 2.0550 X 2.433 =
A. 0.002030 (4) D. 0.004300 (4)
B. 1.005 (4) E. 1000.1 (5)C. 0.00860 (3) F. 230.1 + 2.4234 =232.5 G. 2.0550 X 2.433 =5.000
Mass: the amount of matter that an object containsMeasured in gramsAlways remains constant
Weight: a force that measures the pull of gravity on a certain massMeasurement can change depending on
locationExample: on the moon
DiscoveryEducation Mass Vs. Weight Video Clip
First things first…mass vs. weight
Ratio of mass of an object to it’s volumeIntrinsic property
Depends on the composition of an object, not on the size of the sample
Demo (human density demo)
Density = mass ÷ volumeUnits: g/mL or g/cm3
Density
DensityPhysical property of matterEverything has a unique densityThe measure of the relative "heaviness" of
objects with a constant volumeHow closely "packed" or "crowded" the
material appears to be
VolumeThe amount of space an object takes upUnits of measurement:
LitersMillilitersCentimeters cubed (cm3)
Measuring VolumeWe can measure the volume of regular
object using the formula length x width x height.
10 cm
9 cm
8 cm
Length
Height
Width
_______ X _______ X _______ = ________Length Width Height Volume (cm3)
Measuring VolumeWe can measure the volume of
irregular object using water displacement.
Amount of H2O with object = ______
About of H2O without object = ______
Difference = Volume = ______
Reading a graduated cylinderRead the measurement based on the bottom of the meniscus or curve. When using a real cylinder, make sure you are eye-level with the level of the water.
What is the volume of water in the cylinder? _____mL
A copper penny has a mass of 3.1 g and a volume of 0.35 cm3. What is the density of copper?
Step 1: List Variables
Step 2: List equation Density = mass ÷ volume
Step 3: Substitute and Solve= 3.1 ÷ 0.35 = 8.8571
g/cm3
Practice
Known Variables Mass = 3.1 g Volume = 0.35 cm3
Unknown Variables Density= ?
A student finds a shiny piece of metal that she thinks is aluminum. In the lab, she determines that the metal has a volume of 245 cm3 and a mass of 612 g. Calculate the density.
Density = 612 ÷ 245Density = 2.50 g/cm3
More Practice
A bar of silver has a mass of 68.0 g and a volume of 6.48 cm3. What is the density of silver?
Density = 68.0 ÷ 6.48 Density = 10.5 g/cm3
One More…
Density VideoBuoyancy- an upward
force exerted by a liquid, gas or other fluid, that
opposes the weight of an immersed object