Materials 

Stretching – the truth!

You may wonder why we study springs and why questions about stretching springs appear on exams. Sure, springs are used in the world, but are they really so important? Why is it important to know how springs stretch when they are pulled?

Well, first, springs are incredibly useful. When made from elastic materials, such as most metals, springs stretch when pulled and return to their original size when released. They can also be compressed and, again, return to their original size when released. The stretching or compression stores energy that is then returned when the spring is released. This energy storage and return is the key reason springs are useful. Springs use this capability in all sorts of applications, including in high tech areas such as automotive, industrial tools and robotics, to more everyday items such as trampolines, mattresses, children’s play equipment, door handles and retractable pens. 

The second reason is that the way that springs respond to force being applied to them (i.e. being pulled or mass added to one end of them) is identical to how materials in general behave. If materials are pulled, then they stretch. The coiled shape of a spring, though, means that the ends tend to move large distances compared to a regular shape of the same material (e.g. a simple rod). This means that studying what happens to springs when they are pulled allows simple measurements to be performed that give us understanding of how all materials behave when they are pulled. Materials behave this way in any application where they have force applied to them, e.g. in construction, vehicles, heart valves, body implants, plants, rocks, furniture, tools, footwear – the list goes on and on. And don’t forget this includes your body too!

Use this experiment to find out more!

Follow these instructions or download the Quick Guide via the link (requires log in):

1. Click on 50 g or 100 g masses to add them to the mass holder.
2. Click on the ruler to go to a zoomed view (centimetre scale).
3. Click on the masses on the holder to move them back to their boxes.
4. To change to a different spring:

• Remove all mass from the holder.
• Click on the spring.
• Select from Low, Medium, High or Unknown Stiffness.
• Click again on the spring to return to main screen. 

5. To change to a different part of the Solar System: 

• Remove all mass from the holder.
• Click on the poster to choose where to do the experiment!

6. Click the Information button to see the controls.

Use this experiment to:

• Test Hooke’s law.
• Measure spring constants.
• Test the ‘limit of proportionality’ for springs.
• Calculate the stored energy of a spring.
• See how different strengths of gravity affect the weight added to a spring.

Download the full Instructions for the Hooke's Law experiment from the link (requires log in)

There are lots of activities to do with the Hooke's Law experiment. You can choose these from one of our Activities, with step-by-step instructions, and record your work on a Worksheet, or use the shorter descriptions in our Questions. Download all of these from from the links (requires log in)

Download the file from the link below to see the full scientific Background to the Hooke's law experiment (requires log in)

Learning Resources

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There are lots of ways that we use materials that see them change temperature. Some examples include heating systems in buildings (especially storage heaters), simple household appliances such as an iron or an oven, combustion engines in cars, jet engines in aircraft, high speed machines such as drills, and industrial furnaces; however, examples also include applications where the temperature is reduced, for example in refrigerators, freezers and heat sinks, which are used to help cool another component.

A change in a material’s temperature will also result in a change in its heat energy. Different materials, however, will have a different change in heat energy for a given change in temperature.

The materials property we use to show this difference is called specific heat capacity. This property is key to allowing us to understand how components will perform in thermal applications and help us to choose the most appropriate material. If you go to study Physics or Engineering at university you will probably also learn how specific heat capacity values depend on a material’s types of atom, atomic bonding and electrical properties.

Download the attachment to see the one-page quick guide (requires login) 

Download the attached file to see the full instructions for this experiment (requires login)

There are two files to download here, both requiring a login first.

The 'Activities' download gives full step-by-step instructions for four activities with this experiment

The 'Worksheets' download provides worksheets for these four activities that can be printed out and written on directly. 

Download the attached file to see the scientific background to this experiment (requires login)

Learning Resources

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The thermal conductivity of materials is hugely important for how we live today.

Thermally-insulating materials are found in lots of places around the home. This includes safety items such as oven gloves or fire blankets and inside ovens and refrigerators to stop them heating or cooling the rest of your kitchen! Your hot water pipes and water heating system will probably have thermal insulation around them to stop unwanted heat loss. Houses and other buildings usually have thermal insulation around them to reduce heat loss when it is cold outside and reduce heat entering when it is very hot outside. This is important as we try to reduce CO2 emissions from energy use as part of our fight against climate change. Insulating materials are also used around industrial furnaces, in refrigerated vehicles and packages (e.g. for transporting food or medical supplies) in aircraft to keep crew and passengers warm in the cold air, and in spacecraft to stop the insides reaching temperature extremes and protecting the spacecraft itself from burning up if it re-enters Earth’s atmosphere.

Thermally-conducting materials are also very important to heating and cooling systems, such as heating elements in kettles and furnaces, radiators, high speed industrial machines and heat-sinks found in electronic devices.  

Heat conduction is also really important in many renewable energy technologies, such as solar cells (photovoltaics), which work less efficiently if they heat up, and ‘thermoelectric generators’ (TEGs), which are most efficient if they conduct electricity well but conduct temperature weakly.

This huge range of applications means there is a lot of research and development of materials with new thermal conduction properties. How materials conduct heat is also related to their atomic-scale structure – this means that we can learn about the materials from how they conduct heat and change their structure in order to create new properties that are better suited for particular applications. There’s so much to find out! For now, why not start with the FlashyScience Thermal Insulation experiment?

Click below to download the Quick Guide pdf (requires login)

Click below to download the Thermal Insulation Instructions (requires login)

The instructions and worksheets for the following activities can be downloaded using the links below (requires login):

Activity 1: Effect of a material as thermal insulation

Activity 2: Comparison of different materials as thermal insulation

Activity 3: Effect of material thickness on heat conduction

Activity 4: Effect of temperature difference on its rate of change (Advanced Experiment) 

Click below to download the Thermal Insulation Background pdf (requires login)

Learning Resources

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