Home > Physics > Keeping Warm or Cold: Insulation and Conduction

Keeping Warm or Cold: Insulation and Conduction

By: Suzanne Elvidge BSc (hons), MSc - Updated: 29 Jan 2019 |
Heat Cool Cold Freeze Conduction

Heat travels through solids by conduction (see also ‘Detecting Fake Silver: Conductivity of Metal’). Insulation can keep things warm and keep things cool by reducing heat transfer through conduction. Insulation can also help reduce heat loss through convection (the way heat travels through liquids and gases) and radiation (the way heat travels through empty spaces).

Conductors and Insulators

Heat travels solids by conduction. The heat energy makes the molecules in the solid vibrate. This vibration, the heat energy, is passed along to the next-door molecules, which then pass it along, until the heat spreads through the whole object. Some substances, like metal, are good conductors, and feel cold to the touch, and some are good insulators, such as wood and plastic, and feel warmer to the touch.

Keeping Warm: Conduction

Put a metal spoon in a mug and pour hot water into the bottom of the mug. See how long it takes for the heat to conduct through the handle. Try it with a wooden spoon.

Heat travels through a radiator or through cooking pans by conduction (see also ‘Detecting Fake Silver: Conductivity of Metal’).

Keeping Cool: Insulation

Insulation protects people from burning – oven gloves protect hands from heat conducted through metal baking trays, and wooden and plastic handles protect from the heat from pans and cooking utensils.

Insulation keeps food cool in fridges and freezers, or in cool boxes and cool bags on picnics, or on the trip home from the shops.

Put two plastic dishes of water in the freezer. Once they have frozen solid, put one in a cool box or cool bag and leave the other one at room temperature for a few hours. Take the ice out – what is the difference?

Keeping Warm: Insulation

Fill a tray with damp sand and put it in the freezer until it is frozen. Take it out and put a piece of polystyrene or a couple of layers of knitted wool (a hat or gloves) on the frozen sand. Fill two containers with water, put one straight onto the frozen sand and put the other on to the polystyrene or wool. Leave for half an hour and take the temperature of the water in the two containers. Which is cooler? Insulation in the form of socks and shoes protects feet from the cold of the ground.

Fill three similar plastic bottles with warm water and take the temperature. Screw the lids on, leave one at room temperature, and put one in a lidded cardboard box on its own, and put the third in a lidded cardboard box surrounded by torn up newspaper or paper from a shredder. Leave for a few hours and take the temperature again – which is warmer? Try with different kinds of insulation – wool, straw, dry hay, cotton wool, sand, feathers or towels.

This technique is used in a form of low energy cooking called ‘hay box cooking’. Find a cardboard box with a lid that is big enough to take a small lidded pan. Put some water, stock and some chopped up vegetables (for example, carrots, potatoes, turnip, peppers, peas) in a pan with a tight fitting lid and carefully bring it to the boil. Check the temperature and then put the pan in the box and surround it with lots and lots of insulation material (whatever worked the best in the previous experiment, underneath and on top as well. Close the lid of the box and leave it for about eight hours.

Take the pan out carefully (it will still be hot) and take the temperature. What is it? Are the vegetables cooked?

You might also like...
Share Your Story, Join the Discussion or Seek Advice..
[Add a Comment]
My son is doing a science project and he has to use a can good can, so he's using an empty can of corn and he needs to insulate it with whatever material he wants and it has to keep water cold and hot. What is the best material to do this?
Ms.Jenny - 15-Oct-18 @ 1:19 AM
What are some good insulators to keep a plastic water bottle warm?
laur - 15-Oct-15 @ 11:07 PM
Its very use ful for me Because ihave to keep a 250 ml beaker with hot water to stay warmfor a scince test
apple - 6-Jun-12 @ 4:45 AM
For a science fair project what would be a good insulator to keep an ice cube from melting and plastic cups or a box
gen - 8-Nov-11 @ 1:44 AM
Can insulation box keep things warmer for a long time?
vinayak - 19-Aug-11 @ 3:18 AM
It was very good- and my pendulum reported rightly to it too!
Professor Calculus - 9-Aug-11 @ 11:48 AM
Share Your Story, Join the Discussion or Seek Advice...
(never shown)
(never shown)
(never shown)
(never shown)
Enter word:
Latest Comments
  • Rea
    Re: Making an Emulsion
    I have always wondered about the Earth. My teacher gave us this website to read about why water and oil don't mix. I started looking around on…
    16 May 2019
  • Candytashy
    Re: Looking at Soil Profiles
    Thanks so much for this post .it really helped me .made my homework much easier and l have learnt a lot from this post
    25 March 2019
  • Rajput
    Re: Pulling and Pushing: Magnetic Attraction
    Kya kisi chemical ko copper me mix karne se iron or steel ko push kiya ja sakte hai. Yadi ho to formula batye.
    25 March 2019
    Re: Soap and Detergent Chemistry
    Thanks you so much because you help different students especially science who went be a perfect a part of chemistry
    22 March 2019
    Re: Soap and Detergent Chemistry
    Thanks you so much because you help d/f students especially science who went be a perfect a part of chemistry like me.
    22 March 2019
  • Ban
    Re: Pulling and Pushing: Magnetic Attraction
    Sir, I found that in magnet the needle attract one side and repulsive other side pls give me the answer
    6 March 2019
  • falcon
    Re: Growing Plants in Different Soils
    this has been very helpful for my science experiment thank you
    19 February 2019
  • Suzwriter
    Re: A Bending Bone
    The bones soaked in water won't change - it's the acid that affects the bones. And eating acid foods doesn't change the pH of the body so won't…
    12 February 2019
  • soloh
    Re: Melting Points for Different Solids
    Could you please practically research whether candle wax can melt at room temperature under reduced pressure?
    6 February 2019
  • asli
    Re: A Bending Bone
    vinegar has acid so if we eat something that contains acid which is bad for bones so what will happen if we eat something that contains Acid!?
    14 January 2019