There were many stages I had to undertake in order to complete my experiment, and make it successful. The stages of the experiment were as follows:
- I collected all the apparatus
- I heated enough water for all three cups
- I poured 100ml of water in a measuring cylinder, and marked the level of water with a pen
- I inserted the boiling water into the cup, until it reaches the line marked with the pen
- With the thermometer in the cup, I began the stopwatch when the temperature of the water reached 90°
- I recorded the temperature of the water, every two minutes, on a table of results
- I repeated this for thirty minutes (15 readings)
- I repeated this procedure for the other two cups
Apparatus
I used the following equipment for my experiment:
- Stopwatch
- Measuring Cylinder
- Thermometer
- 3 cups (Polystyrene, Plastic, & Paper)
- Kettle
- Glass Beaker
- Water (for 3 separate cups)
Safety Precautions
We followed many safety precautions, in order to protect ourselves. These were:
- Using glass beakers, to hold cups in. This avoids the suffering of burns.
- Utilising a big space in order to prevent accidents.
- Having the teacher’s heat and pour the water from the kettle.
- Being strictly restricted to staying in our area of space, as opposed to wandering around.
- No equipment was left on the tables.
Evaluation
The data was collected in the following way:
We were given three separate cups; Polystyrene, Paper, and Plastic. Boiling kettle water was poured into each cup by our teacher. Each cup began at 90°, in order to make it a fair and successful experiment.
In order to collect the data correctly and appropriately, a timer and thermometer was given. Every two minutes, we checked the timer and the thermometer and recorded the temperature of the boiling water. We continued this process fifteen times, until thirty minutes had passed.
After we, as a group had collected three different results for each cup, we calculated an average for each cup. Our three results and the averages were then converted onto graph paper, giving us four separate graphs.
I believe there were a few ways in which I could have improved my experiment.
The first way in which I could have improved my experiment was to place lids on the cup. This would result in a more accurate experiment, as the convection currents would only come out of the sides of the cups.
Another way, in which I could have improved my experiment, was by doing all three experiments at the same time. This way, I could have made sure that the test was fairer, as the room temperature would have been exactly the same, throughout the experiment.
A third way in which I could have improved my experiment was by repeating the experiment, twice more, in order to calculate a better mean average, and increase the reliability of the experiment.
I could have also prevented inconsistent air currents, by enclosing the place in which the investigation took place.
Reliability of Conclusion
Throughout this experiment, I have analysed the three cups, and I have tested their rate of cooling.
The paper cup cooled the fastest, which meant it is the worst insulator of
heat. It cooled faster, as it has the thinnest material.
When I compare my results to my prediction, I have come to the conclusion that my results have successfully matched my predictions.
The graphs of my experiment show fairly decent results. They show smooth curves, and straighter smooth curves, due to the varying rate of heat loss in different cases. The graphs, therefore suggest that the rate of heat loss decreases as time increases.
Considering the way in which I collected the data, I am fairly happy with the data I collected. I am happy with the majority of results, as no major anomalies can be seen. My results have also enabled me to come to a successful conclusion to which cup cools the fastest.
If I were to re-do the experiment, I would make a few changes, as suggested in the evaluation. I made the best use of the available equipment, but as my evaluation suggests, I could have improved my experiment in a few ways.
The lack of scatter on my graph also shows that my results are reliable.
Overall, I believe that my conclusion is the correct one. My curves suggest that the results are reliable and accurate. The trends in my results suggest that as time increases, the temperature of the water decreases.
Reliability of Evidence
I think that my results are fairly accurate. I can see this from my graphs, in which the error bars do not show large margins of error, therefore suggesting my results are accurate. The experiment we did was repeated three times. This was to ensure we could calculate a better average. Looking at my three sets of results, I do not notice much difference, therefore again suggesting my results are accurate, and my experiment was a success.
My results are not completely accurate however, due to the few anomalies. These anomalies could have occurred due to a number of reasons, such as mistiming when recording the results.
There are ways in which I could have avoided these anomalies, which I have mentioned in the evaluation. This includes repeating the number of times we did the experiment, and placing lids on the cups.
After analysing my graphs, I notice that there is not much scatter in my results and the majority of my results are within range. This again enables me to suggest my results are accurate.
Summary of Evidence & Conclusions
The purpose of this experiment is to investigate the rate of cooling in three different cups – Paper, Polystyrene, and Plastic.
I predict that of the three cups, the Plastic cup will release heat the quickest, as it has the thinnest layer, which allows heat to escape at a much faster rate.
Plastic Cup:
My results suggest that the Plastic cup initially cooled down the quickest.
The plastic cup, however, was placed in a beaker, which may have affected the rate of cooling.
Paper Cup:
The paper cup cooled the fastest, which therefore leads me to suggest that it is the worst insulator of heat. This may have been due to its thin material.
Convection, Conduction, & Radiation led to the paper cup cooling down slowly, as air began to get into the cup.
Polystyrene Cup:
After analysing my graphs and results, I have reached the conclusion that polystyrene is the best insulator of heat, as it cooled the slowest. This was most likely due to the small holes in the polystyrene cup, which allows it to trap air.