3. Nylon stockings to provide the insulation.
4. Sellotape to attach the nylon stockings to the boiling tube.
5. Kettle for heating the water needed for the experiment.
6. Two digital thermometers to measure the temperature changes accurately.
7. A stop-clock to record time.
Safety precautions: -
§ Hand gloves for handling hot water
§ Make sure that the boiling tubes containing hot water are properly fixed to the stand.
Factors that affect how well an object keeps warm: -
« Insulation – insulating a surface would decrease the rate of heat loss.
« Thickness – the thicker the surface, the lesser the heat loss.
« Colour – dark surfaces are good emitters of heat and light or shiny surfaces are poor emitters but good reflectors of heat.
« Surface Area – the bigger the surface area, the greater the heat loss.
I have chosen to investigate the effect of insulation on the rate of cooling. The material I am going to use for the insulation is a nylon stocking and this is because it is very practical.
The independent variable is Insulation because I am investigating the effect of insulation on the rate of cooling.
The dependent variable is Temperature because I am investigating the rate of cooling on the effect of insulation.
Factors I am going to keep the same: -
Þ Thickness
Þ Colour
Þ Surface Area
I will keep these factors the same by using the same size and type of boiling tube. By keeping the other factors constant, I can find out the exact rate of change in temperature due to insulation.
¨ I am not going to carry out any repeats due to lack of time.
Setting up of the Equipment: -
ª The boiling tubes are set up in a stand so that they are secure.
ª I am using a digital thermometer because it is more accurate than an ordinary one.
Measurements I am going to make: -
§ I am going to measure the temperature over a time period of 10 minutes so I have a better idea of the rate of cooling.
§ The timer being digital, records the temperature each second. This gives me a very accurate reading also.
Things that did not behave according to my expectations: -
« I expected the rate of cooling under insulated conditions to be slower than what it actually was.
« I did not make any changes to my original plan.
« The experiment could be done in a more temperature-controlled atmosphere such as a fully covered enclosure. This is how my plan could be improved.
Results Table: -
What I kept the same – fairness: -
Þ I used the same size boiling tubes.
Þ Volume of water.
Þ A fixed period of time to measure the rate of change.
Calculations using equations :-
Insulated Boiling Tube
T1 – Temperature at the beginning
T2 – Temperature at the end
Loss of heat = T1 – T2
Conclusion :-
¨ A slower rate of fall in temperature is noted in the case of water under insulated conditions.
¨ Insulation reduces the rate of heat loss.
¨ My conclusion has matched my prediction pretty well. The results show that the heat loss is at a lower rate under insulated conditions.
Evaluating Evidence :-
ª My method was a sensible way of testing my prediction because I started at normal conditions and same parameters were used.
ª My results are reliable because I used a digital timer and the rate of accuracy is higher than by taking the measurements manually. A digital tmer could accurately record the rate of fall of temperature because it records the temperature for every second.
ª I could have done my experiment in controlled conditions if possible to make my results even more reliable.
ª The thermometer fell out of the uncovered tube for a few seconds and it was put back again and this could have been avoided for a more accurate result.
ª My evidence supports my conclusion. I could have increased the thickness of the material used for insulation and this would give a lower level of heat loss and therefore, the difference between the temperature in the insulated tube and the uncovered tube would be more evident.
ª I could repeat my experiment and take an average to increase accuracy.
ª Thermometer should not touch the glass; otherwise it is measuring the temperature of the glass, not the water.
ª Stirring the water would allow an average temperature to be recorded, not a local temperature.
