The Coffee problem 
Based on an activity in 'Data logging in Practice'
Here's the problem...
The telephone rang as I was making the coffee. I like my coffee hot-ish, so should I add the milk now or 5 minutes later, after I took the call?
Any ideas?
One way of dealing with this is to make a guess and hope you're right. Another is to deal with the problem scientifically and do an experiment.
My experiment
So I got a couple of cups, two egg-cups full of milk and boiled the kettle. I got my data logger and two temperature sensors plugged in and ready too. Next I poured hot water into the cups and added milk to one of them. About five minutes later I added the milk to the second cup and took temperature readings for a few more minutes. Finally, I transferred the readings to the computer. I did not stir the cups at any point.
My results
Questions
Open the Coffee results file to analyse these results with your data logging software or spreadsheet. My results file is a SID (or CSV) text file.
- At what time did I add the hot water to the cups?
- At what time did I add the milk to the first cup?
- At what time did I add the milk to the second cup?
- Which graph line shows the cup where I added the milk after a call?
- Look back at my problem. Would it be better to add the milk before, or after the call?
- Take readings from the graph to see how much of a temperature difference this makes? What do you think? Was it worth the trouble?
- Do you think I should have stirred the cups? Why didn't I?
- As a good kitchen scientist, I made sure the experiment was done very scientifically. List the things that I must have done.