/*! This file is auto-generated */ .wp-block-button__link{color:#fff;background-color:#32373c;border-radius:9999px;box-shadow:none;text-decoration:none;padding:calc(.667em + 2px) calc(1.333em + 2px);font-size:1.125em}.wp-block-file__button{background:#32373c;color:#fff;text-decoration:none} Problem 6 A certain diet doctor encourages... [FREE SOLUTION] | 91影视

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A certain diet doctor encourages people to diet by drinking ice water. His theory is that the body must burn off enough fat to raise the temperature of the water from \(0.00^{\circ} \mathrm{C}\) to the body temperature of \(37.0^{\circ} \mathrm{C}\). How many liters of ice water would have to be consumed to burn off \(454 \mathrm{~g}\) (about \(1 \mathrm{lb}\) ) of fat, assuming that this much fat burning requires \(3500 \mathrm{Cal}\) be transferred to the ice water? Why is it not advisable to follow this diet? (One liter = \(10^{3} \mathrm{~cm}^{3} .\) The density of water is \(\left.1.00 \mathrm{~g} / \mathrm{cm}^{3} .\right)\)

Short Answer

Expert verified
Approximately 94.6 liters of ice water are needed, which is impractical.

Step by step solution

01

Identify given values

Determine the values provided in the problem. We have:- Initial temperature of water: \(0.00^{\circ} \mathrm{C}\)- Final temperature of water: \(37.0^{\circ} \mathrm{C}\)- Energy required to burn 454 g of fat: \(3500 \mathrm{Cal}\) and note that \(1 \mathrm{Cal} = 1000 \mathrm{cal}\)- Density of water: \(1.00 \mathrm{g/cm^{3}}\)- 1 liter = \(1000 \mathrm{cm^{3}}\)
02

Convert required energy to calories

Convert the energy required from Calories to calories:\[ 3500 \mathrm{Cal} = 3500 \times 1000 \mathrm{cal} = 3500000 \mathrm{cal}\]
03

Determine the energy needed to heat 1 g of water

Use the specific heat formula: \( q = mc\Delta T \). The specific heat of water \( c \) is \( 1 \mathrm{cal/g^{\circ}C} \). The temperature change \(\Delta T\) is \(37.0^{\circ} \mathrm{C} - 0.0^{\circ} \mathrm{C} = 37.0^{\circ} \mathrm{C}\).Thus, \( q = 1 \mathrm{g} \times 1 \mathrm{cal/g^{\circ}C} \times 37.0^{\circ} \mathrm{C} = 37 \mathrm{cal}\) to heat 1 g of water.
04

Calculate the mass of water needed

With \(37\mathrm{cal} \) needed to heat 1 g of water, determine the mass of water needed to absorb \(3500000\mathrm{cal}\):\[ \text{mass of water} = \frac{3500000 \mathrm{cal}}{37 \mathrm{cal/g}} = 94594.59 \mathrm{g}\] or 94.595 kg.
05

Convert mass of water to volume

Given the density of water is \( 1.00 \mathrm{g/cm^{3}} \) and 1 liter = 1000 g, the volume of water needed is:\[ \text{volume} = \frac{94594.59 \mathrm{g}}{1000 \mathrm{g/L}} = 94.595 \mathrm{L} \]
06

Evaluating the feasibility of the diet

Realize that consuming 94.595 liters of ice water is impractical and potentially harmful. It's far more effective and realistic to focus on a balanced diet and regular exercise for weight loss.

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Key Concepts

These are the key concepts you need to understand to accurately answer the question.

Specific Heat Capacity
The specific heat capacity is a fundamental property in thermodynamics. It defines how much energy is required to raise the temperature of a substance. For water, the specific heat capacity is around 1 cal/g掳C. This means that to increase the temperature of 1 gram of water by 1掳C, you need 1 calorie of energy.
When you鈥檙e heating up water from 0掳C to 37掳C, the specific heat capacity formula helps calculate the amount of energy needed. The formula is given by: \[ q = mc\triangle T \] where:
  • q is the heat energy (in calories)
  • m is the mass of the substance (in grams)
  • c is the specific heat capacity (in cal/g掳C)
  • \triangle T is the temperature change (in Celsius degrees)

In our exercise, for 1 gram of water, setting the values gives:
\[ q = 1 \text{ g} \times 1 \text{ cal/g掳C} \times 37 掳\text{C} = 37 \text{ cal} \] Note how easy it is to calculate for 1 gram but essential to scale up for larger quantities next.
Energy Conversion
Energy conversion is another crucial concept here. Different units measure energy, such as calories (cal) and Calories (Cal), where 1 Calorie is equal to 1000 calories. This often causes confusion because they sound similar but represent different amounts of energy.
In our exercise, we were given the energy required in Calories, and we had to convert it to calories for compatibility with specific heat calculations. The conversion works like this:
\[1 \text{ Cal} = 1000 \text{ cal} \]Therefore, when the problem states that burning 454 g of fat provides 3500 Cal, converting it to calories: \[3500 \text{ Cal} \times 1000 = 3500000 \text{ cal} \] This amount represents the total energy we need to transfer to the ice water.
Density and Volume Calculations
Density and volume calculations often go hand-in-hand, especially in problems involving fluids like water. Density (蟻) is defined as mass per unit volume: \[ \rho = \frac{m}{V} \] For water, the density is usually 1.00 g/cm鲁, meaning 1 gram of water occupies 1 cm鲁.
In our exercise, after determining the mass of water required to absorb 3500000 cal (from earlier steps), we need to convert this mass back to volume to understand how much water is involved. Given the density of water and converting mass (grams) to volume (liters):
  • mass of water needed: 94594.59 g
  • 1 liter of water = 1000 g
Hence, the volume of water needed:
\[ \text{volume needed} = \frac{94594.59 \text{ g}}{1000 \text{ g/L}} = 94.595 \text{ L} \] Realizing this considerable volume highlights the impracticality and health concerns of attempting such a diet to lose weight through ice water consumption.

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Most popular questions from this chapter

A chef, on finding his stove out of order, decides to boil the water for his wife's coffee by shaking it in a thermos flask. Suppose that he uses tap water at \(15^{\circ} \mathrm{C}\) and that the water falls \(30 \mathrm{~cm}\) each shake, the chef making 30 shakes each minute. Neglecting any transfer of thermal energy out of the flask, how long must he shake the flask for the water to reach \(100^{\circ} \mathrm{C}\) ?

It is an everyday observation that hot and cold objects cool down or warm up to the temperature of their surroundings. If the temperature difference \(\Delta T\) between an object and its surroundings \(\left(\Delta T=T_{\mathrm{obj}}-T_{\mathrm{sur}}\right)\) is not too great, the rate of cooling or warming of the object is proportional, approximately, to this temperature difference; that is, $$ \frac{d(\Delta T)}{d t}=-A(\Delta T) $$ where \(A\) is a constant. (The minus sign appears because \(\Delta T\) decreases with time if \(\Delta T\) is positive and increases if \(\Delta T\) is negative.) This is known as Newton's law of cooling. (a) On what factors does \(A\) depend? What are its dimensions? (b) If at some instant \(t_{1}=0\) the temperature difference is \(\Delta T_{1}\), show that it is $$ \Delta T=\Delta T_{1} e^{-A t_{2}} $$ at a later time \(t_{2}\).

. Steam What mass of steam at \(100^{\circ} \mathrm{C}\) must be mixed with \(150 \mathrm{~g}\) of ice at its melting point, in a thermally insulated container, to produce liquid water at \(50^{\circ} \mathrm{C} ?\)

How many grams of butter, which has a usable energy content of \(6.0 \mathrm{Cal} / \mathrm{g}(=6000 \mathrm{cal} / \mathrm{g})\), would be equivalent to the change in gravitational potential energy of a \(73.0 \mathrm{~kg}\) man who ascends from sea level to the top of Mt. Everest, at elevation \(8.84 \mathrm{~km}\) ? Assume that the average value of \(g\) is \(9.80 \mathrm{~m} / \mathrm{s}^{2}\).

alcohol has a boiling point of \(78^{\circ} \mathrm{C}\), a freezing point of \(-114^{\circ} \mathrm{C}\), a heat of vaporization of \(879 \mathrm{~kJ} / \mathrm{kg}\), a heat of fusion of \(109 \mathrm{~kJ} / \mathrm{kg}\), and a specific heat of \(2.43 \mathrm{~kJ} / \mathrm{kg} \cdot \mathrm{C}^{\circ}\). How much thermal energy must be transferred out of \(0.510 \mathrm{~kg}\) of ethyl alcohol that is initially a gas at \(78^{\circ} \mathrm{C}\) so that it becomes a solid at \(-114^{\circ} \mathrm{C} ?\)

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