By Amanda C. Lee
A few days ago, my physics teacher introduced a new concept to the class. Relating to our work, energy, and power unit, she brought up the question: “can you cook a chicken by slapping it?” This question stems from a recent Reddit post under the tag r/nostupidquestions. Now this seems like a pretty obvious answer: no, how could a chicken be cooked with your bare hands? At least, until it was posted on Facebook, where a physics major, Parker Ormonde, was able to rationalize the answer.
To start, you have to know the formula for converting between kinetic energy and thermal energy: ½mv2 = mcΔT, where m = mass, v = velocity, c = specific heat capacity, and ΔT = change in temperature. Keep in mind, this theory only works if ALL kinetic energy from the slap is converted into thermal energy.
Calculations
Ormonde determined that the average human hand weighs about 0.4kg, and that the average slap has a velocity of 11m/s. Plugging these values into our formula results in: ½(0.4kg)(11m/s)2 = mcΔT, or 24.2kgm2/s2 = mcΔT. Since kgm2s2 can also be conveyed as joules (the unit for measuring energy), the units convert into 24.2J = mcΔT. Ormonde then recognized that an average 1kg rotisserie chicken has a specific heat capacity of 2720J/kgºC. The formula has now made it to 24.2J = (1kg)(2720J/kgºC)(ΔT), or 24.2J/2720JºC = ΔT. Thus, ΔT = 0.0089ºC. This value represents the temperature increase associate with 1 average slap on a frozen chicken (initial temperature of 0ºC). Then, he stated that the frozen chicken must reach a temperature of 205ºC to consider it cooked. We can calculate the number of slaps needed by dividing 205ºC by the temperature increase of 0.0089ºC.
Conclusion
Ultimately, Ormonde came to the conclusion that it would take 23 034 average slaps to cook a chicken. He went further to state that cooking a chicken in one slap would require a velocity of 1665.65m/s. This is obviously quite humanly impossible, considering that the fastest manned jet in the world reaches a maximum of 980.56m/s. Its impossibility also may be for the best, as I doubt anyone would want to eat a chicken that has been slapped 23 000 times. So, while cooking a chicken with our bare hands may not be possible as of today, I find comfort knowing that physics can explain how it could be possible under the right circumstances.
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