/*! 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 13 A cubical piece of heat-shield t... [FREE SOLUTION] | 91Ó°ÊÓ

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A cubical piece of heat-shield tile from the space shuttle measures 0.10 \(\mathrm{m}\) on a side and has a thermal conductivity of 0.065 \(\mathrm{J} /\left(\mathrm{s} \cdot \mathrm{m} \cdot \mathrm{C}^{\circ}\right) .\) The outer surface of the tile is heated to a temperature of \(1150^{\circ} \mathrm{C},\) while the inner surface is maintained at a temperature of \(20.0^{\circ} \mathrm{C}\) . (a) How much heat flows from the outer to the inner surface of the tile in five minutes? \((\mathrm{b})\) If this amount of heat were transferred to two liters \((2.0 \mathrm{kg})\) of liquid water, by how many Celsius degrees would the temperature of the water rise?

Short Answer

Expert verified
Heat flow: 220.95 J; Temp rise: 0.0263°C.

Step by step solution

01

Understand the formula for heat transfer

The heat transfer through a solid is described by the formula: \[ Q = \frac{k \cdot A \cdot (T_2 - T_1) \cdot t}{d} \] where \(Q\) is the heat transferred, \(k\) is the thermal conductivity, \(A\) is the area through which heat is being transferred, \(d\) is the thickness of the material, \(T_2\) and \(T_1\) are the temperatures on each side of the material, and \(t\) is the time for which the heat is being transferred.
02

Calculate the area and thickness

The tile is cubic with side length \(0.10\, \text{m}\). The area of one side \(A\) is \(0.10 \times 0.10 = 0.01\, \text{m}^2\). The thickness \(d\) of the tile is \(0.10\, \text{m}\).
03

Determine the temperature difference and time

The temperatures \(T_2\) and \(T_1\) are \(1150^{\circ}C\) and \(20^{\circ}C\) respectively. Thus, \(T_2 - T_1 = 1150 - 20 = 1130^{\circ}C\). The time \(t\) in seconds for five minutes is \(5 \times 60 = 300\, \text{s}\).
04

Calculate the heat flow using the formula

Substitute \(k = 0.065\, \text{J/(s}\cdot \text{m}\cdot \text{C}^{\circ})\), \(A = 0.01\, \text{m}^2\), \(T_2 - T_1 = 1130^{\circ}C\), \(t = 300\, \text{s}\), and \(d = 0.10\, \text{m}\) into the heat transfer formula: \[ Q = \frac{0.065 \times 0.01 \times 1130 \times 300}{0.10} = 220.95\, \text{J} \]
05

Understand the formula for temperature change in water

The heat required to change the temperature of a substance is given by: \[ Q = m \cdot c \cdot \Delta T \] where \(Q\) is the heat, \(m\) is the mass, \(c\) is the specific heat capacity, and \(\Delta T\) is the change in temperature. For water, \(c = 4.186 \text{J/g}\cdot\text{C}^{\circ}\).
06

Calculate the temperature change of the water

We have \(Q = 220.95\, \text{J}\), \(m = 2000\, \text{g}\) (since 2L of water is 2000g), and \(c = 4.186 \text{J/g}\cdot\text{C}^{\circ}\). Rearrange the formula: \[ \Delta T = \frac{Q}{m \cdot c} = \frac{220.95}{2000 \times 4.186} \approx 0.0263^{\circ}C \]

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Key Concepts

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

Thermal Conductivity
When we talk about thermal conductivity, we're discussing how well a material can conduct heat. Imagine it as a highway for heat flow. Some materials let heat zoom through quickly, while others slow it down. The thermal conductivity (\(k\)) measures this capability. In our exercise, the heat-shield tile from the space shuttle has a thermal conductivity of 0.065 \(\text{J/(s}\cdot\text{m}\cdot\text{C}^{\circ})\), meaning it's not an excellent conductor compared to metals like copper but does allow some heat to pass.If you think about it: - Higher thermal conductivity means better heat conduction. - Lower thermal conductivity suggests insulation properties.The thermal conductivity is used in the formula for heat transfer: \[Q = \frac{k \cdot A \cdot (T_2 - T_1) \cdot t}{d}\]Here, we multiply the thermal conductivity by the area, the temperature difference, and the time, then divide by the thickness. Knowing this, you can see how materials with high thermal conductivity transfer heat effectively over time.
Temperature Change
Temperature change, symbolized as \(\Delta T\), tells us how much the temperature of a substance increases or decreases. It's essential in understanding how substances react when they gain or lose heat. In the shuttle tile example, the importance is in the difference between the outer and inner surfaces. That difference (\(T_2 - T_1\)) is 1130\(^{\circ}C\), a significant amount that drives heat across the tile.This concept is crucial when analyzing:
  • how much heat energy is required to cause a change in temperature,
  • the efficiency of heat transfer,
  • and the impact on substances receiving heat.
By calculating the temperature difference, we ensure that the tile can handle extreme conditions, simulating how it protects the spacecraft by allowing only some heat to pass through.
Specific Heat Capacity
Specific heat capacity (\(c\)) tells us how much heat is needed to raise the temperature of a given mass by one-degree Celsius. Each material has its own specific heat capacity, indicating its ability to absorb heat.For water, a commonly used reference example, the specific heat capacity is \(4.186 \text{J/g}\cdot\text{C}^{\circ}\). This means that to raise 1 gram of water by 1\(^{\circ}C\), you need 4.186 Joules of energy.In the context of the exercise:
  • We've determined that 220.95\(J\) of heat was available from the tile,
  • Water's specific heat capacity shows us how this heat changes its temperature.
By using the formula \(Q = m \cdot c \cdot \Delta T\), we rearrange it to solve for \(\Delta T\) and find out how much the water's temperature increases after receiving that specific heat. Here, it resulted in a minor change of about 0.0263\(^{\circ}C\), showing water's resilient heat holding capacity.

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Most popular questions from this chapter

Light bulb 1 operates with a filament temperature of 2700 \(\mathrm{K}\) whereas light bulb 2 has a filament temperature of 2100 \(\mathrm{K}\) . Both filaments have the same emissivity, and both bulbs radiate the same power. Find the ratio \(A_{1} / A_{2}\) of the filament areas of the bulbs.

Due to a temperature difference \(\Delta T\) , heat is conducted through an aluminum plate that is 0.035 \(\mathrm{m}\) thick. The plate is then replaced by a stainless steel plate that has the same temperature difference and cross sectional area. How thick should the steel plate be so that the same amount of heat per second is conducted through it?

A closed box is filled with dry ice at a temperature of \(-78.5^{\circ} \mathrm{C}\) while the outside temperature is \(21.0^{\circ} \mathrm{C} .\) The box is cubical, measuring 0.350 \(\mathrm{m}\) on a side, and the thickness of the walls is \(3.00 \times 10^{-2} \mathrm{m} .\) In one day, \(3.10 \times 10^{6} \mathrm{J}\) of heat is conducted through the six walls. Find the thermal conductivity of the material from which the box is made.

An object is inside a room that has a constant temperature of 293 \(\mathrm{K}\) . Via radiation, the object emits three times as much power as it absorbs from the room. What is the temperature (in kelvins) of the object? Assume that the temperature of the object remains constant.

A baking dish is removed from a hot oven and placed on a cooling rack. As the dish cools down to \(35^{\circ} \mathrm{C}\) from \(175^{\circ} \mathrm{C},\) its net radiant power decreases to 12.0 \(\mathrm{W}\) . What was the net radiant power of the baking dish when it was first removed from the oven? Assume that the temperature in the kitchen remains at \(22^{\circ} \mathrm{C}\) as the dish cools down.

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