Tensile Strength

1. Tensile Strength
Aim
To be able to test various physical
properties

2. Context
Different ways a material can be used will
depend on its physical properties. These
include strength, density, hardness and
conductivity.
You are going to measure the strength and
density of some materials to help you decide
which might be the best material to make a
racing bicycle from.

3. Risk
Assessment

4. Equipment
Diagram

5. Method
Testing Strength
1. The material to be tested needs to be held firmly between the two
vices. (see diagram – click here)
2. Use a micrometer to measure the diameter of the wire.
3. Repeat your measurement of the diameter of the wire.
4. Now calculate the average value for the diameter.
Use the formula: area = /4 × (diameter)2.
Write down the average value in your results table
5. Add masses to the mass holder until the wire breaks.
6. Write down the mass attached to the wire at the breaking point.
Include the mass of the lower vice and mass holder. Write down the
value of the mass in your results table.
7. Repeat steps 1 to 6 for three other materials (a wire made
of another metal, nylon thread, fibreglass).
8. Calculate the tensile strength of each material tested. Assume that a
mass of 1 kg has a weight of 10 N.

6. Method
Testing Density
1. Measure the mass of a piece of metal using a balance. Write down the
mass in your results.
2. Pour enough water into a measuring cylinder to cover the piece of
metal. Write down the volume in your results. Remember that 1 ml
is 1 cm3.
3. Now put the piece of metal into the water. (The water should cover
the piece of metal. If it doesn’t you will need to go back to step 2
and make sure you put enough water into the measuring cylinder.)
Write down the level of the top of the water, which is the total
volume of the water and the piece of metal. Write down your
readings in your results.
4. Repeat steps 2 and 3 and write down your readings in your results.
Now you can calculate the average value for the volume of the piece
of metal.
5. Repeat steps 1 to 4 for three other materials.

7. Results for tensile strength
Tensile strength (Nm
-2
)
Breaking force (N)
Breaking mass (kg)
Average diameter (mm)
Average diameter (m)
Cross-sectional area (m
2
)
Diameter of wire (2)
Diameter of wire (1)
Material

8. Results for density testing
Average volume of material
(cm
3
)
Density(mass/volume)(gcm
-3
)
Density (kgm
-3
Volume of material (2) (cm
3
)
Volume of water + material
(2) (cm
3
)
Volume of water + material
(1) (cm
3
)
Volume of material (1) (cm
3
)
Volume of water (2) (cm
3
)
Volume of water (1) (cm
3
)
Mass (g)
Material

9. Analysis
The order of strengths of the materials tested is………..
Measurement of the tensile strengths is important because …
…………
The order of densities of the materials tested is………..
Measurement of the densities is important because …………
…
The material I would chose to build a racing bike is …
This is because …………..

10. Evaluation
My experiment went…
I did not have problems with… because…
I had problems with … because…
To improve my experiment I could…
My results would be more reliable if I…
Did you have any results that look out of place? If so, how might
this have happened?