Physics 

What is ‘Tensile Testing’?

The ‘tensile’ properties of a material describe its most basic mechanical behaviour – how much does a material stretch when it is pulled and how much of the stretching is permanent? ‘Tensile Testing’ is the process of measuring a material’s tensile properties.

Why are tensile properties important?

Understanding of tensile properties is vital for any application that uses materials structurally, i.e. to withstand or apply force. The range of uses this covers is enormous. Strong and stiff structures are used in vehicles (cycles, cars, trains, aeroplanes, spacecraft), bridges and buildings, sports equipment and bio-implants (e.g. hip joint replacements). Flexible materials are also used in many of these applications. Thin but robust materials are used in touchscreens. Hard materials are used in machines and robots that process and shape other materials and as durable coatings that improve the performance and lifetime of aerospace and bio-implant components. Elastic materials can be stretched enormously before any permanent change is made and are used in springs and high performance fabrics. And it’s not just how a component is used – many manufacturing processes involve changing a component’s shape or response to applied forces, e.g. extrusion to make tubes, beams and bottles; drawing to make springs or wires; or forging and rolling to shape and harden metals.

To select a sample:

• Click the lower jaw to go to the sample view.
• Open the calliper jaws, drag a sample of choice between the jaw and fully close the jaws around it. In this LITE version you can only select one of the samples)
• Use the Vernier scale to measure the sample width.
• Click the sample held in the callipers to use it in the tensile testing machine
• Or open the callipers, return the sample to its original position and choose another sample. (Only available in the full version)

To set the strain increment:

• Click the Set button (display starts to flash)
• Use the keypad and the Del button to enter the desired Step value
• Click the Set button again (display stops flashing)

To apply strain to samples:

• Set the strain increment value as described above.
• Click the up arrow to increase the applied strain by the Step increment value.
• Click the down arrow to decrease the applied strain by the Step increment value.
• Measure (and record) the applied load (force) using the needles on the Load dial.
• Turn off the strain control unit and click on the lower sample holder to select a new sample.

These instructions can be downloaded below.

Download the file below for the full instructions, including background, relevance, operating instructions and questions.

Structural materials are required to withstand a variety of applied loads in use. Understanding how these materials respond to the applied loads is vital for informed materials selection. Here we investigate how materials behave under tensile loading (loads applied along the length of a material to cause stretching).

The Tensile Test experiment allows a number of mechanical tests to be performed on materials, including:

• Determination of full stress-strain curve to fracture, using either ‘engineering’ or ‘true’ value
• Observation of elastic behaviour and calculation of Young’s modulus
• Observation of the onset of plastic behaviour and permanent deformation
• Calculation of moduli of resilience and toughness
• Calculation of strain energy in a system
• Calculation of work done in deforming a sample

The Tensile Testing experiment can be used for a wide range of investigations.

This downloadable pdf below contains a range of example short and long questions.

We have also provided a spreadsheet file to allow you to enter your SAMPLE WIDTH, STRAIN and APPLIED LOAD data and obtain stress-strain plots. (HINT: to investigate the general form of stress-strain curves with younger students, use a default sample width of, say, 7 mm)

Watch the video above and download the file below to learn about the scientific background of Tensile Tests

Thermodynamics and engine cycles are relevant to most areas of technology and science.

The behaviour of gases is used directly in applications as diverse as compressors, refrigerators, power generation from steam-driven turbines (used in gas-fired, coal-fired or nuclear power stations), pumping of gases (from natural gas pipe networks to aqualungs), and transport vehicles using petrol and diesel engines (combustion engines), jet and rocket engines, high performance tyres (e.g. for F1 cars) and even hot air balloons!

Thermodynamics is relevant far more widely though and to any system in which there is a change in energy, volume or ordering. This is relevant to almost every process around us, from sub-atomic particles forming atoms to the expansion of the universe and taking in atoms bonding to make a molecule or crystal (Physics), molecules reacting with each other (Chemistry), all biological processes (Biology), the weathering of rocks and tectonic plate movement (Geology). Even your breathing while you read this and your eye converting light into electrical signals so you can read
this are thermodynamic processes. All energy technologies, materials manufacturing or recycling, chemical processing, transport technologies and
even information technologies rely upon the principles of thermodynamics.

Thermodynamics and gas laws are, therefore, incredibly important topics. The FlashyScience Gas Laws virtual experiment allows you to start to explore this fascinating area of science and engineering.

Download the attached Quick Guide for easy instructions (log in required)

Also, download the ‘How To’ attachments for step-by-step instructions on conducting experiments for:

• Constant pressure
• Constant temperature
• Constant volume

Download the attached file to see the full operating instructions for the Gas Laws experiment (requires log in)

​Download the attached file to see lots of Gas Laws experiments and questions (requires log in).

Here are a few simple suggestions for you to start exploring how ideal gases behave:

1. Adiabatic changes (P, V and T all variable) - Increase the pressure and observe the effect this makes on the volume and temperature.
   
2. Constant pressure (isobaric) – Charles’ law. Turn on the Heat jacket. Change the temperature and see the effect this makes on the cylinder volume.
   
3. Constant temperature (isothermal). Turn on the Heat Jacket to keep the temperature constant. Change the pressure and see what happens to the cylinder volume.
   
4. Constant volume (isovolumetric) – Gay-Lussac law. Note the initial piston height h₀. Alternately change the pressure when the Insulation jacket is in place and then adjust the temperature with the Heat jacket in place to bring the piston back to height h₀. How do P and T vary to achieve this?
   

​Download the attached file to see the Background science behind the Gas Laws experiment (requires log in)

What is ‘Tensile Testing’?

The ‘tensile’ properties of a material describe its most basic mechanical behaviour – how much does a material stretch when it is pulled and how much of the stretching is permanent? ‘Tensile Testing’ is the process of measuring a material’s tensile properties.

Why are tensile properties important?

Understanding of tensile properties is vital for any application that uses materials structurally, i.e. to withstand or apply force. The range of uses this covers is enormous. Strong and stiff structures are used in vehicles (cycles, cars, trains, aeroplanes, spacecraft), bridges and buildings, sports equipment and bio-implants (e.g. hip joint replacements). Flexible materials are also used in many of these applications. Thin but robust materials are used in touchscreens. Hard materials are used in machines and robots that process and shape other materials and as durable coatings that improve the performance and lifetime of aerospace and bio-implant components. Elastic materials can be stretched enormously before any permanent change is made and are used in springs and high performance fabrics. And it’s not just how a component is used – many manufacturing processes involve changing a component’s shape or response to applied forces, e.g. extrusion to make tubes, beams and bottles; drawing to make springs or wires; or forging and rolling to shape and harden metals.

To select a sample:

• Click the lower jaw to go to the sample view.
• Open the calliper jaws, drag a sample of choice between the jaw and fully close the jaws around it.
• Use the Vernier scale to measure the sample width.
• Click the sample held in the callipers to use it in the tensile testing machine
• Or open the callipers, return the sample to its original position and choose another sample.

To set the strain increment:

• Click the Set button (display starts to flash)
• Use the keypad and the Del button to enter the desired Step value
• Click the Set button again (display stops flashing)

To apply strain to samples:

• Set the strain increment value as described above.
• Click the up arrow to increase the applied strain by the Step increment value.
• Click the down arrow to decrease the applied strain by the Step increment value.
• Measure (and record) the applied load (force) using the needles on the Load dial.
• Turn off the strain control unit and click on the lower sample holder to select a new sample.

These instructions can be downloaded below.

Download the file below for the full instructions, including background, relevance, operating instructions and questions.

Structural materials are required to withstand a variety of applied loads in use. Understanding how these materials respond to the applied loads is vital for informed materials selection. Here we investigate how materials behave under tensile loading (loads applied along the length of a material to cause stretching).

The Tensile Test experiment allows a number of mechanical tests to be performed on materials, including:

• Determination of full stress-strain curve to fracture, using either ‘engineering’ or ‘true’ value
• Observation of elastic behaviour and calculation of Young’s modulus
• Observation of the onset of plastic behaviour and permanent deformation
• Calculation of moduli of resilience and toughness
• Calculation of strain energy in a system
• Calculation of work done in deforming a sample

The Tensile Testing experiment can be used for a wide range of investigations.

This downloadable pdf below contains a range of example short and long questions.

We have also provided a spreadsheet file to allow you to enter your SAMPLE WIDTH, STRAIN and APPLIED LOAD data and obtain stress-strain plots. (HINT: to investigate the general form of stress-strain curves with younger students, use a default sample width of, say, 7 mm)

Watch the video above and download the file below to learn about the scientific background of Tensile Tests

Radioactive elements (radionuclides or radioactive isotopes) produce high energy particles and are used in a huge range of applications. Most people know about nuclear power, which converts the energy of radiation from uranium-238 or plutonium-239 into heat and then electrical power, even in small-scale form for remote applications (e.g. spacecraft). There are far more widespread uses all around us though.

Radionuclides are used in many medicinal applications. They can be used as tracers to follow fluid flow inside the body by detecting the radionuclide emitted radiation (e.g. technetium-99, thallium-201, iodine-131 and sodium-24) Medical imaging can use radioactive elements that naturally collect in particular parts of the body and image the radioactive emission. For example, iodine-131 is used to image the thyroid and other isotopes can be used for other organs, such as bones, heart, liver and lungs. Larger doses of the radionuclides (e.g. cobalt-60) are used to create a targeted radiotherapy treatment of cancer in these organs. It is even possible to detect the presence of Heliobacter pylori (an unwanted bacterium that can be in stomachs) with a simple breath test that uses carbon-14.

You may have radioactive materials in your home, school or workplace. Smoke detectors use alpha radiation from americium-241 to ionise smoke particles for detection. Glow-in-the-dark inks on clocks, watches and emergency signs that convert radioactive particle energy from promethium-147 into light.

You may also have food that has been treated with radiation. Many foods (including tomatoes, mushrooms, berries, cereals, eggs, fish and some meat products) are irradiated with gamma rays from cobalt-60 to kill micro-organisms and improve the food’s shelf life (without making the food radioactive!). Similarly, gamma radiation from caesium-137 is used to sterilise medical products such as syringes, heart valves, surgical instruments and contact lens solutions.

Radioactive elements are used in industry too. For example, the absorption of different types of radiation mean it can be used to monitor the thickness of manufactured components and sheets. Radionuclides are also used for detecting leaks from pipes, the direction of underground pipes and waste dispersal in the environment. Radioactive sources are also used in industrial imaging, with the sample placed between the radiation source and a detector. Certain isotopes are used as chemicals in order to trace chemical reaction routes, e.g. carbon-14 in photosynthesis. Similar approaches are used in biology to test when proteins undergo important ‘phosphorylation’ reactions (using phosphorus-32) to learn when their function is activated by other proteins or small chemicals.

Radioactive elements can also be used for historical dating of objects, e.g. carbon-14 dating for estimating the age of organic matter and uranium-238 for rocks. Similarly, radioactive decay from vintage drinks such as wine can be used to prove their age, since radionuclides were released into the atmosphere by nuclear explosion tests after World War II and are present in all food and drink produced since then.

With so many uses, it’s no wonder that radioactive decay is an important aspect of science and engineering!

Select the radiation source:

• Click on the Source holder
  
• Click on one of the radiation sources in the tray and then in the holder
  

Detecting radiation:

• Click the power switch on the Geiger-Müller counter.
  
• Read the needle position on the dial to measure level of radiation.
  

Changing the filter material and thickness:

• Click on the filter holder
  
• Click on the material of choice to increase its thickness in the holder by 1 mm
  
• Click on the material in the holder to reduce its thickness by 1 mm
  
• Measure the filter thickness using the markings inside the holder
  

Change the source-detector separation:

• Click and drag the holder mount to move it along the ruler
  
• Measure the mount’s position using the magnified ruler view seen while clicked on the holder mount.
  

Time travel!

• Move time forward by one minute, hour, day, month or year by clicking on the appropriate value on the clock
  

Open the file below to see the full instructions for operating the Radiation experiment

Download the file below to see example experiments, including for GCSE and A-level.

Or see if you can do some of the following:

• Measure the half-life of different sources (GCSE)
• Measure how detected gamma radiation varies with source-detector separation
• Find out how alpha, beta and gamma radiation is absorbed by various materials
• Explore multi-decay type radioactive sources

Download the file below to see the scientific background of radioactive decay.