Contributed by: Engineering K-Ph.D. Program, Pratt School of Engineering, Duke University

Lesson: Floaters and Sinkers

density , displacement , buoyancy , x-y scatter graph

Keywords

Students will be able to define density as the amount of mass per volume a material contains.

Students will be able to calculate the densities of objects when given their masses and volumes.

Learning Objectives 

Students will be able to compare the densities of several common materials.

Students will be able to explain that materials that are denser than water ordinarily sink, while those less dense than water will float.

Look at these three cubesPass them aroundWhat is different about the three?How would you calculate density?

Example

Density = Mass/Volume

Specifically Mass should be in grams and volume in either mL or cm3

mL = cm3

Introduction

Density is a measure of how much stuff (matter) there is.

NOT how big something is OR how heavy.

A room full of feathers is heavier than a bucket full of fishing weights.

Organize the following from most dense to least dense. FeathersRed BrickAluminumStyrofoamButter

Assessment 

In groups of 3 determine the density of the block I give you.

MaterialsRulerElectronic ScaleDensity block

Activity

When your group has calculated the density write a description of the material and also the density on the board with the greatest density on top and the least dense object on the bottom.

Activity Continued

Toy CarRubber stopperGolf TeeMetal WeightGolf BallC ClampGlass Marble

Densities of Irregular shaped objects.

What would the density be of the following. Brick with a volume of 1000 mL

and a mass of 3500 grams?

Block of aluminum with a volume of 10 mL and a mass of 350 grams?

Which is more dense?