Newton's law of cooling and your body

In summary, using Newton's law of cooling, we can estimate the time of death by finding the temperature of the body at a later time based on the ambient temperature and initial temperature. The heat transfer coefficient for a human body at rest is approximately 2.1 W/m^2\cdot K and the surface area is about 1.7 m^2. The general form of the solution to Newton's law of cooling is T(t)=T_a+\left(T_0-T_a\right)\exp[-hAt], where T_a is the ambient temperature and T_0 is the initial temperature of the body.
  • #1
captainjack2000
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Homework Statement


a body has temperature 27C at twelve oclock. The room temperature is constant at 16C. Two hours later the body was found to have a temperature of 24C. The temperature of a normal human body is 37C.Using Newton's law of cooling estimate the time of death.


Homework Equations


Newton's law of cooling says that the rate of heat loss from a body is proportional to the temperature difference between it and the surroundings.
dQ/dt=hA(Te-Tb)
where Te is the temp of the environment 16C=289K and Tb is the temp of the body 24C=297K. I am not sure what the heat transfer coefficient h is or how to determine this. Also not sure how to use the fact that normal body temperature is 37C

Could someone please give a bit of a start in the right direction
Thank you
 
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  • #2
Think of Newton's law of cooling in this form:
dT/dt = -k(T - Te)

What's the general form of the solution to that equation?
 
  • #3
After some googling, the heat transfer coefficient for an idle body is [tex] 2.1 W/m^2\cdot K[/tex] and the approximated surface area is [tex]1.7 m^2 [/tex].

As for solving this, you'd need to integrate your equation (which btw should be [tex]dT/dt[/tex], not [tex]dQ/dt[/tex] and find the temperature at a later time [tex]t[/tex] is

[tex]
T(t)=T_a+\left(T_0-T_a\right)\exp[-hAt]
[/tex]

where [tex]T_a[/tex] is the ambient temperature and [tex]T_0[/tex] is the initial temperature of the body.
 

1. How does Newton's law of cooling apply to the human body?

Newton's law of cooling states that the rate of heat loss of an object is directly proportional to the difference in temperature between the object and its surroundings. This applies to the human body as well, as our bodies lose heat to the environment through conduction, convection, and radiation.

2. Why does our body temperature decrease when we are in a cold environment?

Our body's natural response to a cold environment is to conserve heat and maintain its internal temperature. This is achieved through vasoconstriction, where blood vessels in our skin narrow and reduce heat loss, and shivering, which generates heat through muscle contractions. However, if the body is unable to generate enough heat, our core temperature will eventually decrease.

3. How does the body regulate its temperature in a hot environment?

In a hot environment, our body's natural response is to release heat through vasodilation, where blood vessels in our skin widen to allow for increased blood flow and heat loss through sweat production. This helps to maintain our body's internal temperature within a safe range.

4. Does Newton's law of cooling apply to all parts of the body equally?

No, the rate of heat loss can vary depending on the body part and its surface area. For example, our head, hands, and feet have a higher surface area-to-volume ratio, making them more susceptible to heat loss compared to our core.

5. How does age and health affect our body's ability to regulate temperature?

As we age, our body's ability to regulate temperature decreases due to a decrease in muscle mass and a decrease in sweat gland function. Certain health conditions, such as hypothyroidism and diabetes, can also affect our body's ability to regulate temperature. Medications and alcohol consumption can also impact our body's ability to maintain its internal temperature.

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