How to cook a chicken with bare hands? Beat the chicken for 13 hours and 37 minutes

As a good friend of mankind, chickens are of great significance on our dining table. How to cook a chicken is also a science, emmmm, I mean how to "cook" a chicken. Common methods include frying, stewing, grilling... You may have seen these, but have you ever thought about how to cook a chicken by slapping it?

On Valentine's Day 2019, an ID called "MrWaterplant" asked a question on the reddit forum: "Since kinetic energy can be converted into heat energy, can I cook a chicken by slapping it?"

Seeing this kind of question, you will naturally have questions: Why are you thinking about this question on Valentine's Day? How much hatred do you have against chickens? And, is this really possible?

Actually, this question that looks like a joke is actually a good physics question.

There have been some similar questions online before, such as the online comic xkcd created by Randall Monroe, which answered the question "From how high can a steak be dropped so that it is cooked when it hits the ground?" The result is that 250 kilometers may be the best height to get a medium-rare steak. Below 250 kilometers, the steak is more raw. Above 250 kilometers, it will enter the "erosion zone" of the ballistic missile, and the steak will be burnt and disintegrated.

A similar question is "From how high does a frozen turkey need to be dropped so that it is cooked by the time it hits the ground?" I happened to have calculated this question in 2010, and concluded that a height of 14.2 kilometers might be enough.

You can see that the two results are quite different, but estimates are not without error. Anyway, let's look at the physics of slapping a chicken.

Cooking is heating

For example, if you want to cook a chicken, you can roast it, fry it, boil it, or even microwave it. The key is that you have to heat the chicken from room temperature to 74 degrees Celsius.

There are two benefits to cooking chicken. First, cooked meat is easier for humans to digest, and we consume more calories from cooked meat than raw meat. Second, at 74 degrees Celsius, most of the harmful bacteria on the chicken are killed. So, don't eat raw chicken.

Although a cooked chicken is not just raw chicken at a higher temperature, I will assume that it is. Cooking changes the chicken in more ways than just changing its temperature, but let's ignore that for now. The question we are interested in is how much energy is required to change the temperature of the chicken? To answer this question, let's look at the change in thermal energy.

The amount of heat energy depends not only on the change in temperature, but also on the mass and type of the object. Written as a formula, it looks like this: Heat energy change = mass × specific heat capacity × temperature change.

In this formula, ΔT refers to the change in temperature and C is the specific heat capacity.

What is "specific heat" C? Let me give you an example: suppose I want to heat the same mass of steel and foam. The steel and foam have the same initial temperature, but it takes more energy to heat the steel because the specific heat of steel is 0.49 J/(g•°C) - this unit is read as joules per gram per degree Celsius, while the specific heat of foam is only 0.3 J/(g•°C).

What about chickens? What is the specific heat capacity of a chicken? I don't know the value, so I can only guess, so I'll use the value of water, 4.186 J/(g•°C) (water has a very high specific heat capacity). Or I can use something similar to a chicken. How about a turkey? Turkey is similar to a chicken, right? I happen to have measured the specific heat capacity of a turkey.

Here's how to determine the specific heat capacity of a turkey:

Get a turkey (you need to know its mass and initial temperature beforehand)

Place it in an insulated box with some hot water.

After a while, measure the temperature of the water and the turkey.

Since I know the specific heat capacity of water, I can use the temperature drop of the water to calculate the increase in heat energy of the turkey. Below is a temperature curve (to prove that I really calculated it).

I calculated that the specific heat capacity of turkey is 6.018 J/(g•°C). I didn't expect it to be higher than water.

Conservation of Energy: From Slaps to Heat

Assuming that chickens and turkeys are similar, I can calculate the change in heat energy required to cook a chicken. But where does this heat energy come from? That's right, from the slapping of a hand.

So how much energy does a slap provide? Assuming the mass of your hand is mh and the speed of your hand is v, the kinetic energy K of a slap is:

When your hand hits the chicken, it stops. Its kinetic energy is now zero, so its previous kinetic energy must have gone somewhere. Most of that kinetic energy probably went into the chicken—and into your hand! In other words, to cook the turkey, you have to cook your hand, too. But let's not worry about the hand for now; just estimate that half of its energy went into the chicken and half stayed in the hand.

So how many shots should you take?

If you hit the chicken enough, it will not only die, but also be cooked | knowyourmeme.com

The main concept is there, now all that's missing is the calculations.

Let's make some initial assumptions:

→ Mass of chicken = 2 kg. This is roughly what a whole raw chicken you buy at the store weighs. Don't worry, if you don't like this number, you can change it below.

→ Initial temperature = 23 degrees Celsius, target temperature = 74 degrees Celsius.

→ The mass of the palm = 200 grams (this is just a blind guess).

→ How about the speed of the slap = 3 meters per second? Let's speed it up a bit and make it 5 meters per second.

→ Energy factor = 0.5. This is the fraction of the energy from the slap that goes into the chicken. I’ll use the symbol “f” to represent this. Now I can calculate the temperature change of the chicken after a slap.

It can be calculated that the temperature rise caused by each slap = 1.03855×10-4 degrees Celsius

Number of slaps required = 4.91069×105

This means that you have to pat the chicken 49,000 times to cook it through, provided that you pat it very quickly.

If you clap once a second for 13 hours and 37 minutes, the chicken will be almost cooked. (Remember to take some measures to cool your palms, after all, cooked palms are not good.)

But if you take thermal radiation into account, the energy lost in the flapping must be calculated using the Stepan-Boltzmann equation. Physics is tricky (but fun).

Maybe you don't agree with my assumption. You can change the value at will and recalculate. Yes, the value can be changed, no big deal.

For example, Parker Ormonde on Facebook estimated the mass of a human hand to be 400 grams and the speed of a slap to be 11 meters per second. He calculated that 23,034 slaps are enough. If you want to slap someone in one go, the speed would have to be 1,665.65 meters per second.

I slap you at 1.6 kilometers per second, and you might die | knowyourmeme.com

After solving the problem of cooking a chicken with bare hands, there are only three unsolved mysteries left:

What is the mass of a human hand? Feel free to measure it, but don't do anything bad.

How much do netizens like “unconventional cooking methods”?

How much free time do physicists have?

By Rhett Allain

Translation: Porco Rosso

Editor: You Shiyou

Title image from youtube/Jixcx

Compiled from: Rhett Allain. (2019). How Many Times Do You Have to Slap a Chicken to Cook It? https://www.wired.com/story/how-many-times-do-you-have-to-slap-a-chicken-to-cook-it/Slaps Chicken at 3275.95 MPH. (2019). https://knowyourmeme.com/memes/slaps-chicken-at-327595-mph