Practice Assignment 11
Measuring the densities of sports equipment materials
You can make measurements of different materials to explore the differences between them, such as their densities. The uses of a material depend strongly on its density. For example, many items of sports equipment – such as tennis racquets – use low density material even when it is relatively expensive.
Here you will measure the density of three specimens of sports material. You will then compare your measurements with measurements made by other students using different materials.
What you have to do
- Get copies of Standard Procedure SP0011-1:2005, SP0011-2:2005, SP0011-3:2005. Make a table like this one to summarise how each method is useful.
| Method | Can it be used for specimens with regular shape? | Can it be used for specimens with irregular shape? | Can it be used for specimens that float on water? |
|---|---|---|---|
| SP 0011-1:2005 | |||
| SP 0011-2:2005 | |||
| SP 0011-3:2005 |
- Before starting:
- read the standard procedure and the hints below carefully;
- check that a risk assessment has been done;
- list the equipment and materials you need.
- Work with three specimens of a single sports equipment material. Label the specimens A, B and C.
- For each specimen, decide which method to use to measure its density. Make the necessary measurements and calculate the density. Record your results in a table like this:
| Specimen | Standard Procedure used | Mass in grams | Volume in cubic centimetres | Density in grams per cubic centimetre |
|---|---|---|---|---|
| A | ||||
| B | ||||
| C |
- For one of your specimens, determine its density again using a different method. Record your measurements in a table as before.
- Compare your different measurements. Try to explain any differences in results for the same material.
- Combine your results with those from groups who have used different materials. Use the information to make a bar chart to compare the densities of at least six different sports equipment materials.
Some hints
- It is important to give values with correct units. If you measure mass in grams and volume in cubic centimetres then use ‘grams per cubic centimetre’ for density.
- For each sample, use the simplest method that will work.
- Note that:
- all three methods are suitable for measuring regular shapes;
- the method described in SP0011-1:2005 is not suitable for measurements of irregular shaped objects;
- the method described in SP0011-3:2005 is not suitable for specimens that float.
Some questions
Don’t forget to write up your results in your Laboratory Notebook.
- Do all of the specimens of the same material have the same density?
- Does the size of a material specimen affect the density value?
- Do all of the materials have the same density?
- Find out the density of water. Name a material that is denser than water and a material that is less dense than water.
- Find out where you would look for information on densities of metals. Use a computer to make a bar chart to compare the densities of at least five pure metals and at least one alloy.
- For each of the regular shaped specimens:
a. convert the mass to kilograms (instead of grams);
b. convert the lengths to metres (instead of centimetres);
c. calculate the volume in cubic metres;
d. calculate the density in kilograms per cubic metre (kg m-3). - How do the densities in kg m-3 compare with values in g cm-3 ?
- There is a standard formula for calculating density. Make up a memory aid to help you to remember it.
- Look back at what you have done. Suggest what you could have done better.