Radiation
This is infra red rays vibrating the particles next to them giving them more energy and therefore making the water warmer. The water particles at the top of the pan will radiate the heat into the air.
Factors I will need to consider.
A lid
There will be a great difference in the speed of heat loss if I use a lid. This is because of the large amount that will be lost by convection. Due to this I have decided to do it with a lid on
Volume of water used
I will use 50ml cup, as when there is a large volume of water used, it will stay warmer for longer than if there were a low volume of water. This will stay the same throughout
Insulation
On one of the tests insulation will be on the cup as our experiment is to see which is best
So taking all this into account I predict that with insulation as in the cotton wool there will small pockets of trapped air. I also think that gases are better insulators than solids because particles are further apart making it harder to pass on vibrations.
Equipment
The equipment I will use timer, cup, thermometer, cotton wool elastic band and kettle
Safety
To ensure my experiment will be safe I will keep my hands away from boiling water and will clean up any spillages
Fair Test
To make this a fair test I must ensure that same volume of water is used, same size cup, same temp of water. Keep a lid on both experiments
Method
- Collect all equipment that is needed as shown in the apparatus
- Wrap the cup in cotton wool and leave on without insulation
- Boil kettle
- Pour 50 ml of boiling water in cup
- Put in the thermometer and start the clock
- Record temperature every minute for 5 minutes
- Repeat experiment for more accuracy
Results
Experiment 1 with insulation
Minutes Temperature
Room temp 24
Min 1 95
Min 2 93
Min 3 91
Min 4 89
Min 5 86
Experiment 2 with insulation
Minutes Temperature
Room temp 24
Min 1 94
Min 2 92
Min 3 90
Min 4 87
Min 5 85
Experiment 1 with no insulation
Minutes Temperature
Room temp 24
Min 1 89
Min 2 86
Min 3 82
Min 4 78
Min 5 76
Experiment 2 with no insulation
Minutes Temperature
Room temp 24
Min 1 90
Min 2 87
Min 3 83
Min 4 80
Min 5 74
I have also shown my results in a line graph
Conclusion
From my results table and graph I am conclude that with insulation on the coffee cup it stays at a higher temp for a longer period. This is quite apparent if you look at the results, as there is a smaller decrease than with no insulation. In my prediction I had said this I had said that with cotton wool it would stop conduction, convection and radiation due to the air pockets in the cotton wool. There were a few mishaps through as we didn’t wait for the coffee cup to cool down on our experiment with no insulation as we were in a rush this could explain the slightly higher temperature records. I was correct in the prediction. From this I am able to conclude that:
1. Heat loss is reduced when there is an insulator wrapped around the cup
2.Small pockets of air is a good insulator
Evaluation
A big safety concern before the experiment was the temperature of the water so we made sure it didn’t succeed 100c. I feel that I was precise when measuring the volume of liquid and temperature. Also I measured the temperature with a thermometer to the nearest degree and measured the time to the nearest second. I didn’t take enough readings for my liking due to insufficient time. I didn’t really obtain any anomalous results as they all went down in a similar pattern. To improve my experiment I could of used a clamp to keep the thermometer in place as it could be at different temperatures at different places. By doing these I would of kept my experiment much fairer. I could of also tried some other insulators in my experiment e.g. bubble wrap as this would be excellent as it has a lot of trapped air or black paper of some sort as this is a bad insulator as it would absorb the heat. I could also wrap the insulation round more than once as this would see if more insulation would mean less heat lost