Two Insulators The Rate Of Heat Loss example essay topic

Science Investigation: Insulation Introduction My investigation is to find out the rate of which heat transfer happens. Heat transfer is a process in which energy in the form of heat energy is exchanged between materials that are at a different temperature. Heat is generally transferred by conduction, convection, radiation and evaporation. All of these processes can all happen simultaneously but it is likely that one will give the greater heat exchange. Heat is exchanged through the brick wall by conduction. The surfaces of a high-speed aircraft are heated up by convection.

The earth is heated by heat that is being radiated from the sun. These experiments involved the temperature of hot water being recorded at chosen intervals in a copper can. Here is a description of the following processes that will affect my experiment: Conduction This is where heat energy passes through the walls of the can by making the particles of the can vibrate and then they will make the particles next to them vibrate causing the heat to pass through the walls of the can and out to the surroundings. Materials that are good thermal conductors tend to be good electrical conductors; metals such as gold, silver and copper have high thermal conductivity's and will conduct heat readily. Materials such as glass have much smaller heat transfer values and are poor heat conductors. Convection This is where the cooler water particles sink down to the bottom and the warmer water particles float up to the top.

Convection will only affect my experiment if I did not have a lid. This is because the warm water will float up to the top and the heat energy will escape out of the top. If a pan of water was being heated from below then the water particles at the bottom of the pan will become warm as therefore become less dense, they will begin to rise to the top of the pan. As the warmer water particles begin to rise, the cooler water particles at the top of the pan will sink to the bottom, as they are less dense. Once at the bottom of the pan the will start to get warmer and become less dense. This process will continue until the pan of water is at the same temperature.

Radiation This is when the warm water particles vibrate the water particles next to them. This will give them more energy and will make the water there warmer. The water particles at the top of the can will radiate the heat energy into the surrounding air. For heat to radiate it does not need to be in contact with matter. Heat can radiate for some thing to another body through a complete vacuum, this is how the sun heats up the earth. This process can also be called the Wave Motion.

Evaporation This could cool down the water, as when the water evaporates it will take the heat away with it in the same way evaporating sweat cools down our bodies. If I use a lid this could slow down this process. As the water vapour will not be able to escape into the air as quickly as it would normally keeping the heat in for longer. If I insulate the can with different materials then it will slow down the heat loss, but I cannot stop it. This will be useful for keeping drinks hot.

The materials that I could insulate the copper can that I will be using for my experiment are: Black paper Corrugated card Cotton wool Tin foil I also conducted my experiment without any insulation so I can compare the results between insulated and non-insulated to find out if there is a distinct difference in heat loss. Question to investigate What material /'s offer the best protection against the cold, or, which material /'s is / are are the best insulators. Aim The aim of this investigation is to test three materials (wool, bubble wrap, plain copper), and see which one /'s are the best at keeping in the heat of the hot water in the copper container. Factors There are many factors, which can affect my experiment.

The factors are: If a lid is used, there will be a great difference in the speed of heat loss if I use a lid. This is because a large amount of heat will escape form the top of the container by convection and evaporation. Therefore if I use a lid it will slow down these processes. Also what the lid is made of will make a difference. If a lid is made of paper or card then its insulation properties will be at a minimum, however if the material used for a lid is polystyrene or bubble wrap then the heat loss through the top of the container will slow down. Volume of water used When the volume of water is higher, it will stay warmer for longer than if there was a low volume of water.

This is because when there is a high volume of water then the outside of the water will cool down, but the inside will stay warm. If the container that the water is insulated then it will stay warmer then if the container is not insulated. This is because the insulation will slow down the process of heat loss. If the container does not have insulation then the process will not slow down. If different types of insulation are used then this will affect the heat loss. Materials of high insulation such as bubble wrap or cotton wool will not allow much heat to be transferred through it, however materials of low insulation such as black card will let the heat pass through it quicker.

What the container is made ofThe material of the container could change the rate of heat loss. If it is made from polystyrene it will not allow much heat to pass through it. If it is made of metal then it will allow more heat to pass through it. If the inside of the container is painted will make a difference. If it is painted silver then it reflect some heat back to the water, but if it is painted black it will absorb the heat and pass it out the other side.

Room temperature If the temperature of the room is near the starting temperature of the water then heat process of heat loss will not be as fast. This is because if there is a bigger difference in temperature then the more heat will try to escape. Prediction Out of the two materials that I chose to investigate I think that cotton wool will be the best at reducing the heat loss. I am saying this because inside cotton wool there are many small pockets of trapped air, and air is a very good insulator in small pockets. I also am suggesting that plain copper will be the worst insulator, because the metal will allow the heat to run through it very easily resulting in a rapid heat loss.

I also think that with the two insulators the rate of heat loss will start of fast and over time will slow down. Plan I intend to wrap two containers with the chosen insulators, but leave the last one plain: Cotton wool Bubble wrapping I have also chosen to do a control experiment without insulation to see if there is a great difference in the heat loss if the container has insulation. I will then boil some water and when it is boiled I will carefully pour it into a measuring cylinder up the chosen volume (80 cm). I will pour it into the containers and allow it to cool to the chosen starting temperature. Once it reaches the chosen starting temperature then I will start the stop clock and record the temperature at chosen intervals. I will repeat this procedure for the next two containers.

I will then repeat the whole experiment one more time to be sure that my results that I will obtain are reliable and reproducible. To make this experiment a fair test I will have to keep the following factors the same: Volume of water Starting temperature of water The number of times the insulation is wrapped around the container Material of container Where the thermometer is placed in the water Be careful to protect eyes by using safety goggles If I keep all of these the same my experiment will be a fair one. Safety Safety precautions are needed because I am dealing with hot water, which can scald. The following things need to be acknowledged to, in order to keep this experiment safe: Be careful not to knock over the container with the hot water in Be careful not to knock over other peoples containers Care is needed when pouring hot water Do not run with the container of hot water Apparatus Below is a list of the things that I can use, whiles conducting my experiments: Three 150 ml copper containers Kettle Safety goggles Stop clock 100 ml measuring cylinder Thermometer Corrugated card Cotton wool Bubble wrapping Method Put on safety goggles 2. Collect all the equipment that is needed as shown in apparatus list above 3. Wrap the two containers with the chosen insulators, the third one is left with no insulation 4.

Boil kettle 5. Pour 100 ml of boiled water into measuring cylinder 6. Pour this into one of the three containers 7. Put the thermometer in the water 8. Wait until the water cools down to 90^0 c 9.

Start stop clock 10. Record the temperature every two minutes for 20 minutes 11. Repeat procedure for the other two containers 12. Altogether I tested two materials and I have discovered which have the best insulating properties. In order from the best insulator to the worst: Cotton wool Bubble wrap Plain copper In my prediction I had said the cotton wool would be the best insulator, because it has many air pockets trapped within it and air is an excellent insulator.

I was correct in my prediction. From these statements I therefore conclude that: Heat loss is reduced when there is a insulator wrapped around the container Small pockets of air makes a excellent insulator The colour black is a good conductor of heat Evaluation I feel that I was precise when measuring volumes of liquid and the temperature. I measured the water with a measuring cylinder and measured the liquid as the liquid meniscus just touched the line. Also I measured the temperature with a thermometer to the nearest. 5 ^0 C. I also measured the starting temperature accurately. I measured the time to the nearest second with the stop clock.

Did I take enough readings I did take enough readings as I recorded the temperature once every two minutes for 20 minutes, which gave me 10 results. I repeated the experiment once more and calculated the mean average. This means I had 10 points for each insulator used for the graph therefore it was much more accurate, so my graph was also good. Anomalous results I did obtain several anomalous results.

These results may have been in error because I may have recorded the time at slightly different times when writing down the temperatures. Another reason for the inaccurate results is that I may have moved the thermometer from the middle of the can slightly higher or lower or a little bit to the left or right. Improvements to my experiment As an improvement to my experiment I could have put a corkboard underneath the copper container, as this will have reduced the conduction of heat from the copper container into the table. I could have used a clamp, boss and stand to hold the thermometer in a fixed position; by doing this I could ensure that the thermometer is always at the same place in the water. By doing all of these it would have kept my experiments much fairer. By Daw an Sharif 10 Y.