A 50 -kg person consumes about 2000 kcal of food in one day....

A 50 -kg person consumes about 2000 kcal of food in one day. If 10$\%$ of this food energy is converted to thermal energy that does not leave the body, what is the person's temperature change? What assumptions did you make?

Key Concepts

Energy Conversion Efficiency

This concept refers to the fraction of consumed energy that is transformed into thermal energy and retained in the body. In this context, only 10% of the total caloric intake is assumed to be converted into heat, which directly influences the calculation of the temperature change.

Unit Conversion

Unit conversion is critical here as it involves transforming kilocalories (kcal) to joules (J), the SI unit of energy. This step ensures consistency with the other parameters, such as mass in kilograms and specific heat capacity in joules per kilogram per degree Celsius, in the energy balance equation.

Specific Heat Capacity

Specific heat capacity is a property that indicates the amount of energy required to raise the temperature of one kilogram of a substance by one degree Celsius. The human body is often approximated by the specific heat capacity of water, facilitating the calculation of the resultant temperature change when energy is absorbed.

Energy-Temperature Relationship

The energy-temperature relationship is based on the formula ?T = Q/(m·c), linking the absorbed energy (Q), mass (m), and specific heat capacity (c) to the change in temperature (?T). This fundamental principle of thermodynamics allows one to calculate how much the temperature of a system (or the human body) will increase given a certain energy input.

Assumptions in Energy Calculations

This involves assuming that the human body behaves like an isolated system with uniform temperature, that its specific heat capacity is similar to that of water, and that the thermal energy generated does not escape the body. These assumptions simplify the model and facilitate the calculation but may not capture all the complex physiological heat exchanges occurring in a real-life scenario.

Transcript

00:04 Let's identify the key point of the problem.

00:15 First, we have person with a mass, say m, equal 50 kilograms.

00:38 Number two, the dairy wood energy, wood energy taken.

00:55 Let's say it's a q1, that equal to 1 ,000 kilocalic.

01:04 3.

01:07 Converted thermal energy and that says q2, which is 10 % q1.

01:30 So the problem is to ask, what is the temperature change if q2, which is the thermal energy, does not leave the body.

01:58 Okay, so that's the key point.

02:02 So there are three steps to solve this problem.

02:04 Or we can break this problem into three steps.

02:10 Step one.

02:14 Identify the key concept, also the appropriate equation that required to solve the problem.

02:40 Let's start with the c.

02:43 That is the most important concept of this problem.

02:48 And c is called the symbol stand for specific heat capacity of an object.

03:09 Now that is this symbol has the unit that is a calorie kilogram per kelvin so which means that in order to raise one kilogram of a mass one degree kelvin you need this much of a heat okay so say we have a mass and then we have temperature change.

03:51 Then with the c, then we can calculate the heat required by simply multiply c by m by t.

04:03 So let's say that our equation.

04:12 So we have key concept and the equation to solve the problem.

04:17 Now let's go to step two...

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