Activity 5.3 Determining Density

IntroductionHow full is the bag that you take to each of your classes? Can you put any more stuff into it? What happens to the size of the bag? What happens to the mass of the bag? The size of the bag likely stayed the same, though the bag itself is probably about to burst open. When the volume of something stays the same while the mass increases, then the density increases.

In this activity you will measure volume and mass to determine the density of several objects.

Equipment Engineering notebook Triple beam balance or scale Graduated cylinder Dial calipers Automoblox people and wheels Wooden puzzle cube blocks

Steel spheres Delrin spheres Paper clips (Optional) Aluminum ruler Density and Uses of Common Materials

Chart

ProcedureDetermining the Plastic Materials used in Automoblox Vehicles

Obtain an Automoblox vehicle from your teacher. Study the Automoblox people and the wheels.

1. Are the Automoblox people made of the same material as the Automoblox wheels? Why do you think so? How might you test your hypothesis?

2. You will determine the density of the plastic used to manufacture the Automoblox people and the Automoblox wheels. Measure the mass of the four Automoblox people and wheels. For improved accuracy, measure the four Automoblox people together and then measure the four wheels together. Record values including units to the appropriate number of significant digits.

Automoblox People Automoblox Wheels

Total mass/weight of all sample(s)

(include units)

© 2012 Project Lead The Way, Inc.Introduction to Engineering Design Activity 5.3 Determining Density – Page 1

3. Measure the volume of the four Automoblox figures and then measure the volume of the four wheels. Because of the irregular form of each object, the volume is more easily measured using a graduated cylinder.

a. Add water to the graduated cylinder until it is approximately 2/3 full.

b. Record the water level.

c. Carefully add samples.

d. Record the new water level.

Automoblox People Automoblox Wheels

Water level without samples

(Include units)

Water level with samples

(Include units)

Water volume displaced = volume of sample(s)

(Show calculations)

4. Calculate the density (by hand or using Excel) of the four Automoblox figures and four wheel samples. Complete the table below or attach a print of your Excel worksheet. Be sure to include units with all measurements and quantities.

Automoblox People Automoblox Wheels

Total mass/weight of sample(s)

Volume of sample(s)

Formula for density

Density (SI)

Density (US)

5. Does your data support or refute you hypothesis (from number 1 above)? Explain.

6. Refer to the Common Materials Density and Uses Chart. Use your results to make an educated guess as to the material used in the manufacture of the Automoblox people and wheels. What other tests might further substantiate your guess?

© 2012 Project Lead The Way, Inc.Introduction to Engineering Design Activity 5.3 Determining Density – Page 2

Conclusion1. How can you use density to identify a material?

2. What are limitations of the calculated and indirect volume measurement?

3. Explain the difference between weight and mass.

© 2012 Project Lead The Way, Inc.Introduction to Engineering Design Activity 5.3 Determining Density – Page 3