The tea spoon…

But first…
Dulltown, UK: Today’s dictionary words are: courlan, slaister, ovoviviparous, hypabyssal, ullage, and twinter. Please have these words looked up and placed in suitable sentences ready for Professor Mouldie first thing after breakfast tomorrow morning. Should the professor turn up in, and conduct the lesson from, a palanquin supported by four school prefects, you should not let this distract you from your studies.
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‘Dave, I see that here in the cafe, although you invariably have green tea, without milk of course, you still like to have a teaspoon.’
‘Hm…’
‘I’ll bet you use it to cool the tea – the tea being hotter than ordinary tea that has had a quantity of cool milk added. I see that you place the spoon in the tea so that the metal, which is of course a good conductor of heat, soaks it up and lowers the temperature of the beverage?’
‘Hm…’
‘I observe that a single immersion doesn’t cool the drink enough though, so you put the spoon in and take it out again to cool a number of times, over several minutes.’
‘While I nibble my cake or brownie… You are very observant.’
‘I like to think so Dave…’
‘But my friend, have you noticed that the length of time the spoon is in the cup is noticeably shorter than the time it lounges nonchalantly on the saucer?’
‘Oh, I hadn’t noticed that Dave. Would you care to explain?’
‘Alright… I believe part of it is to do with temperature gradients.’
‘Gradients?’
‘Yes, the tea is pretty hot compared with the temperature of the room…’
‘Of course…’
‘…and when the spoon…’
‘At room temperature?’
‘…goes into the liquid and suddenly has intimate contact with it, it encounters a steep temperature gradient, and being a jolly good conductor, it rapidly heats up.’
‘I see, and when it’s taken out and placed on the saucer?’
‘It holds its heat, and the only way it can lose it is by warming the air around it, which wisps it away in convection currents.’
‘Did you say “wisps”?… The verb to wisp?’
‘I think so…’
‘Dave…’
‘Yes?’
‘Is all this correct? Scientifically?’
‘Thermodynamics… I don’t know.’
‘You don’t know?…’
‘Hm, maybe it loses its heat in the air at the same rate as it gains it in the tea?’
‘So the warming up and cooling down times could be the same then?’
‘Possibly… but then again, the mass of the tea is much greater than that of the wispy floaty air surrounding the spoon, everyone knows that you can store a lot more heat in a large mass than in a small one…’
‘Do they?’
‘Yes, and then again, the spoon heats up by conduction, and loses it by convection… Do you happen to have a decent thermometer on you?’
‘Er, no, I’m afraid not.’
‘A calorimeter perhaps?’
‘I have one at home, but I rarely take it out with me…’
‘We could conduct a little experiment.’
‘What? Right here in the cafe?’
‘Yes.’
‘Would we have to draw graphs?…’
‘Possibly.’
‘I’ve never liked graphs… By the way how is your tea now?’
‘It’s gone cold, too much talking!…’
‘Oh dear.’
‘It’s alright, I don’t mind my tea a bit tepid…’