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

ProcedureSection 1: measuring mass and volumeDemo water displacement in grad. cylinderUse 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 bflWhat 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?