Pre-Lab 2B: Density
Lab requirements: remember?
KQ
Bkgd
Drawing
Skip lines
Section: number
All questions AND answers
Data charts: rules, resolution, units, accuracy
Purpose
• You may be familiar with the trick question
“Which is heavier: a kilogram of feathers or a
kilogram of bricks?” What is the trick?
• In this investigation you will study the
relationship between mass, volume, and density.
• You will also determine how an object’s density
affects whether it sinks or floats in water.
Key Question
• How is an object’s density related to its
volume, mass, and tendency to sink or
float?
Background
Define:
line of best fit
density (formula)
slope (formula)
Drawing
• A kilogram of feathers and an equal mass
of bricks
Procedure
Section 1: measuring mass and volume
Demo water displacement in grad. cylinder
Use 6 objects which are the EXACT SAME (all nuts, or
bolts, or screws);
MUST RECORD TYPE AND COLOR OF OBJECT
Find mass (? Decimals), volume (? Decimals), never put
units IN w/data: on header bar only, why?
How many items are you measuring/why (data chart)?
Graph data: MAKE A LINE GRAPH
Leave room for extending the graph’s BFL up through
the top right: this is a key point, remember it!!!!!!!!
Section 2:
How do you find the best fit line?
What is slope?
Show slope work on graph!!!! Include labeling the
two points w/ coordinates you use on the bfl
What is the formula for slope?
Section 3:
Use your graph’s BFL to predict all six objects’
mass: predict a point from 6th volume to the BFL
line to the y-axis intercept:
show example……..
Section 4:
Use your data and get data from 5 additional lab
groups in table 2, to answer density questions
Section 5:
OMIT: DO NOT DO THIS SECTION
Section 6:
Predict if cubes will float or sink in water:
what is this prediction really called?
must occur before you collect data
What is the density of water?
Section 8:
Test your hypothesis
Post Lab 2B: Density
• You may be familiar with the trick question
“Which is heavier: a kilogram of feathers
or a kilogram of bricks?” What is the trick?
• In this investigation you studied the
relationship between mass, volume, and
density.
• You also determined how an object’s
density affects whether it sinks or floats in
water.
Background
Define:
density (formula)
line of best fit
slope (formula)
• Does density depend on the size of the
material? Evidence?
• Does density depend on the type of
material? Evidence?
• Using what you have observed in this lab,
do you suppose that density depends on
the shape of the material? Why or why
not?
• What is the density of water?
• Describe two different ways you can find
the density of a regularly-shaped object
like a cube.
• Explain why two different objects can have
equal volumes but different masses.
• Which method of prediction was better,
testing the weight of the cube in your
hand, or comparing the density of the cube
to the density of water? Why?