What have you found out?
I have concluded from the results that as the layers of insulation are added, increasing the thickness of the insulation the average temperature drops more slowly.
Are there any patterns in your results?
The average temeperature drop when there has been no layers added and the thickness is zero is the greatest, from then on the average drop declines in relation to the number of layers and thickness increasing. The decline in the average temperature drop from 0 layers (Omm) to 1 layer (2.
8 mm) is the greatest and from there, it seems to be more gradual in decline.
Show how you know about these patterns?
The patterns are shown clearly on the graph as the line is declining. I have drawn a line to represent the gradient on the graph; it shows that from 0mm to 2.8mm there is a dramatic decline in the average temperature drop as the gradient is very steep. The gradient between 2.8mm and 4.
6mm is only slight which shows the average temperature drop when another layer was added was not as a dramatic decline. From then on, as each layer is added, increasing the thickness the decline in the average temperature drop is not as dramatic which is shown from the graph gradient, which is showing a constant decline.
What is the science behind your investigation?
Three factors effect the experiment – conduction, convection and radiation. Conduction can only transfer heat through solids because of the particle formation and so cannot transfer heat through a vacuum, as the particles are too far apart.
Particles in a solid are tightly packed so when the water is warmed up they use the heat energy to move but as they are tightly packed, they can only vibrate vigorously not freely move. The vibrating causes them to bump into neighbouring atoms, transferring the heat through the walls of the can and out to the surroundings. This theory therefore suggests that conduction can occur easily in a solid if there is no barrier between the walls and the outside surroundings. This relates to the results as when the can had no layers the average temperature drop was the greatest as the conduction method took place easily, transferring heat to the surroundings.
As each layer was added more vacuums were being created, making it harder for heat to travel through by conduction thus making it more difficult for the water to cool. A polysterine lid was also added when the first layer was added to stop conduction through the bottom of the can to the table. This could be one reason for the dramatic drop from 0 to 1 layer as the bottom layer is suddenly stopping conduction through the bottom of the can. Another reason for the dramatic decline from 0 layers (omm) to 1 layer ( 2.8mm) is because the particles are suddenly having to work harder to transfer heat to the surroundings, the addition of another layer may not make as much difference because the particles have already built up energy to transfer through the first layer and so another to go through is not as much as a chore.
When the can has no layers it does not have a plastic lid which means heat is lost through convection. Convection can only occur in two types of matter liquid and gas. It cannot take place in a solid because the particles are too close to move. In this experiment the heat is lost from the water to the surroundings by the air above the water becoming warmed and becoming less dense than cold air and so I rising. This cools the water down quicker, increasing the average temperature drop. The hot air that has risen eventually cools down again and falls cooling the water. Convection currents are stopped when the first layer is added and the plastic lid covers the top of the can. As plastic is a solid it does not let convection currents pass. This is probably another reason for the dramatic decline in temperate drop from O layers (O mm) to 1 layer (2.8mm) because heat can no longer be lost through conduction.
Radiation can pass through all types of matter infact radiation does not need any atoms to transfer through as it can travel through a vacuum e.g. the sun’s rays travel through the vacuum of space to Earth through Wave motion. This experiment was conducted with a black can, presuming the can is painted black inside means that it absorbed the warmth of the water through radiation waves into the walls. If black was the colour inside the can it quickened the process of heat loss whereas if the can had been sliver inside it would reflect the radiation waves back to the water prolonging the heat contained.
If you were to continue the investigation would the patterns continue?
If I was to continue with the investigation I think judging from the graph the patterns will continue to a point until it levels off. Past a certain amount of layers there will be no decrease in the temperature drop as the water will reach the point were an extra layer makes no difference. This is because the water will have reached the maximum point were the average temperature drop will not change as the can not retain any more heat than it was already..
How good is the experiment?
The experiment shows an approximately clear rate on how insulation effects the temperature drop on water. The experiment was done more than once on each layer to provide a more accurate average and precautions such as measuring the thickness of the bubble wrap so it would always be the same size tried to ensure that the experiment was fair.
However, there were still things, which hindered the accuracy of the experiment. Ideally the start temperature for each experiment would be the same to give a clearer picture of the results but this would be impossible every time without special equipment.
The bubble wrap that is placed around the can is measured but when it is attached to the can by the amount of three elastic bands there is a chance that it will become slightly compressed therefore compressing the vacuum. If this occurred it would have caused slightly inaccurate results as the thickness of the bubble wrap around the can may not always be the same.
When there is the addition of the lid when the 1st layer is added the thermometer from the diagram seems to be held in place by a resting in the hole through it to the can. As this hole will be in the same place all the time the thermometer will be in the same spot of water each time resulting in results that are more accurate. However, when the can has no layers there is not anything to support the thermometer, this perhaps means that someone held it in the water. This may result in accurate results as the theremometer could touch the side a bottom of the can, taking the temeperature of them not the water. The thermometer in each one of the three experiments with no layers may not have been placed in exactly the same position in the water each time.
The room temperature may have effected the results. If the temperature of the room is near the starting, temperature of the water than the heat loss will be not as fast. The opposite applies for if it was below the temperature, the heat loss may occur slightly more quickly.
If the starting temperature is high then more heat will try to escape at a faster rate because there is more heat energy to move. As in this experiment the starting temperatures are very accurate this theory does not effect it greatly but if a temperature is higher the water may cool quicker than if the temperature is lower.
Are there any odd results?
There is one odd result when 1 layer is added, on the first try at one minute were the temperature rises instead of decreasing. The odd temperature may slightly effect the averages.
What caused the odd results?
It is odd that the temperature has reason as there is not a heat source for the particles to gain their energy from so it is likely that from the previous experiment the thermometer has not been left to cool and is still rising. It is also possible that if from the previous experiment the can had not been left to cool so heat still remained in its walls so it passed by to conduction to the water when it is placed inside causing the temperature to abnormally rise. It is also possible that it was inaccurately read.
Do the results allow you to make a firm conclusion?
I think the results have allowed me to make a firm conclusion because they have produced the patterns I expected. They may be slightly inaccurate here and there but these inaccuracies do not effect the experiment to the extent all the results are abnormal.
If you were to repeat this experiment what would you change and why?
As an improvement to my experiment I could have used a clamp, boss and stand to place the thermometer accurately especially when there isn’t a lid to support it to stop any inaccuracies caused by this. Perhaps it would also be a good idea if the bubble wrap were made marginally thicker before it was wrapped around the can as when it is compressed it will become smaller and go to the correct size. I also think a note of the room temperature should be made just to be aware of an outside factor that may effect the results.
How could you extend this investigation?
I could change the material of the can to see if it affects the rate of which heat is transferred and I could also change the insulation properties by using cling fling or cotton wool to see what difference they make to the temperature loss. You could keep adding layers to see the point were it makes no difference. In addition, you could investigate the experiment without the plastic lid to see the difference the loss of heat through convection currents throughout the experiment changes the results.
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