• blog@thephotonmagazine

How hard do you have to slap a chicken to cook it? — By Rishi S. Papani

Imagine the stress of cooking for a family, a stress which many people go through every day. There is often lots of patience and vigilance required when traditionally cooking, especially when heating meats on a stove. But what if instead of spending minutes waiting for your chicken to fry, you could just slap it once and be done with it. Well that future may not be too far off, and today we will explore the requirements for that scenario. We will be considering the objective requirements to cook the average chicken breast to a safely eatable level, all biological values used (i.e. Weight of chicken) are global averages.

Our chicken breast will be starting at room temperature or 25°C and the minimum temperature to cook chicken breast is 74°C, so we will have to heat our chicken by 49°C in order to safely eat it. To find the energy required to heat our chicken by 49°C we will have to use specific heat, specific heat is the energy required to change the temperature of an object by 1°C. However, specific heat varies from substance to substance and as such the chemical makeup of our chicken is needed. Apart from that, we also need to know the mass our chicken, as heavier objects need more energy to heat up more particles. Chicken breasts on average weigh anywhere from 170 to 226 grams, for the sake of this calculation we will be taking the average of that which is 198g, and its chemical composition is 75% water and 24% protein by mass. This means that 75% percent of our chicken’s mass is water, or 148.5g, and 24% of its mass is protein, or 47.52g. The specific heat capacity of water is 4.2 joules(J) per gram(g) per °C, this means to raise 1g of water by 1°C we need to supply 4.2J of energy. As we have 148.2g of water we will need to multiply our specific heat by 148.2 this gives us 620J, meaning that we need 620J to heat up the water in our chicken by 1°C. The approximate average specific heat of protein is 1.7J per g per °C, as we have 47.52g of protein we will therefore need 72.7J to heat up the protein in our chicken by 1°C. We can add both of these values to get the energy needed to heat our chicken by 1°C, 72.2J + 620J = 692.2J, meaning that we must supply 692.2J to heat up our whole chicken by 1°C. Lastly, we need to heat our chicken by 49°C, this means that we will be heating up our chicken by 1°C 49 times, so we will need 49 times the energy (692.2 * 49) which is 34KJ or 34 thousand joules to cook our chicken.

The primary method of heating our chicken will be slapping it with our hand, and as we now know the energy needed, we can now find out the minimum velocity of our hand. The energy of a moving object is called kinetic energy (K.E.) and is given by the formula (1/2)mv² where m is the mass of the object in kilograms and v is the velocity in meters per second (m/s). As (1/2)mv²= K.E, we can multiply both sides of the equation by 2/m to get v² = 2/m(KE), and then plug in energy and mass to get the velocity squared. The average human weighs 70kg and on average the human hand is 0.58% of the total bodyweight, giving us an average of 406g for the hand however as the equation is in kg we must use 0.406kg. Apart from that, we already know the required K.E. to be 34KJ so when we plug those values into the equation, we get v²=(2/0.406)*(34000) = 167487. As that value is velocity squared we must then take the square root of 167487 to get velocity, which is 409.25 m/s. Therefore, on average we must slap the chicken at 409.25 m/s or 1473.7 kilometers per hour to cook it, for reference the speed of sound is 1224 kilometers per hour which is much smaller than this. However, before you go and slap chicken at the speed of sound, there is one assumption throughout this entire article. We are assuming that all the energy in our slap will be converted to heat energy in the chicken upon impact. In reality this is far from the truth with only a small fraction of our hand’s kinetic energy being converted to actual heat, so the actual value would be much larger than this. Finally to conclude, all the values taken in this scenario are global averages, as we are dealing with biological systems here you will need to adapt these values to you own scenario (i.e. Weight of chicken or mass of hand). As such the author of this article is not responsible for any food poisoning caused by following the procedure mentioned throughout.

  • Facebook Social Icon
  • Instagram