Talk:Newton's law of cooling

Newton's Statement on Cooling

What Newton actually said in Scala Graduum Caloris (1701) was,

"Deinde ponendo quod excessus calorum ferri & particularum rigescentium supra calorem atmosphaerae Thermometro inventum essent in progressione geometrica ubi tempora sunt in progressione Arithmetica, calores omnes innotucre."

Roughly translated, "The temperatures were found to be in a geometrical progression when the times were in an arithmetical progression." --Jbergquist (talk) 09:35, 29 May 2017 (UTC)[reply]

This suggests

T-T_{a}\propto a^{t}

where T_a is the ambient temperature and a<1 or d[log(T-T_a)] =A+Bdt. --Jbergquist (talk) 10:18, 29 May 2017 (UTC)[reply]

In the case of cooling,

T-T_{a}\propto a^{-t}

where a>1. Mikerollem (talk) 11:57, 11 November 2017 (UTC)[reply]

A translation of the passage above is found in Magie, A Source Book in Physics, p. 128.

"Then by assuming that the excess of the heat of the iron and of the hardening bodies above the heat of the atmosphere, found by the thermometer, were in geometric progression when the times were in arithmetical progression, all the heats were determined."

Newton had placed a large block of iron in a fire and heated it to glowing then removed it and allowed it to cool while he placed little pieces of metal on it to determine the temperature at which they solidified.

Also, $T-T_{a}\propto a^{t}\Rightarrow d[\log {(T-T_{a})}]\propto dt$ --Jbergquist (talk) 03:40, 31 May 2017 (UTC)[reply]

Added some punctuation and corrected a typo,

"Deinde ponendo quod excessus calorum ferri & particularum rigescentium supra calorem atmosphaerae, Thermometro inventum, essent in progressione geometrica ubi tempora sunt in progressione arithmetica, calores omnes innotuere."

Mikerollem (talk) 11:31, 11 November 2017 (UTC)[reply]

Q for thermal energy.

The use of the letter $Q$ to represent the thermal energy of a body may upset some people. For historical reasons, it could be linked to the heat tranfer (see Heat and Calorimetry). I suggest to use $U$ instead, for consistency also.--Andrestand (talk) 10:29, 1 June 2017 (UTC)[reply]

dQ/dt Chohil khan (talk) 14:55, 7 January 2019 (UTC)[reply]

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