/*! 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 24 The Kelvin temperature of an obj... [FREE SOLUTION] | 91Ó°ÊÓ

91Ó°ÊÓ

The Kelvin temperature of an object is \(T_{1},\) and the object radiates a certain amount of energy per second. The Kelvin temperature of the object is then increased to \(T_{2},\) and the object radiates twice the energy per second that it radiated at the lower temperature. What is the ratio \(T_{2} / T_{1} ?\)

Short Answer

Expert verified
The ratio \( T_2 / T_1 \approx 1.189 \).

Step by step solution

01

Understanding the Stefan-Boltzmann Law

The power radiated by an object, according to the Stefan-Boltzmann Law, is proportional to the fourth power of its absolute temperature. This can be written as \( P = \sigma A T^4 \), where \( \sigma \) is the Stefan-Boltzmann constant, \( A \) is the surface area of the object, and \( T \) is the temperature in Kelvin.
02

Setting up the Equations for Two Temperature States

Initially, the object is at temperature \( T_1 \) and radiates energy \( P_1 = \sigma A T_1^4 \). When the temperature increases to \( T_2 \), the power becomes \( P_2 = \sigma A T_2^4 \). According to the problem, \( P_2 = 2P_1 \).
03

Substitute and Simplify the Equations

Substitute \( P_2 = 2P_1 \) into the formula to get \( \sigma A T_2^4 = 2 \sigma A T_1^4 \). Simplify by dividing both sides by \( \sigma A \), resulting in \( T_2^4 = 2T_1^4 \).
04

Solving for the Ratio \( T_2 / T_1 \)

Take the fourth root of both sides to solve for the ratio: \( T_2 = (2^{1/4}) T_1 \). Therefore, the ratio \( \frac{T_2}{T_1} \) is \( 2^{1/4} \).
05

Calculating the Numerical Value

Calculate \( 2^{1/4} \). Using a calculator, \( 2^{1/4} \approx 1.189 \).

Unlock Step-by-Step Solutions & Ace Your Exams!

  • Full Textbook Solutions

    Get detailed explanations and key concepts

  • Unlimited Al creation

    Al flashcards, explanations, exams and more...

  • Ads-free access

    To over 500 millions flashcards

  • Money-back guarantee

    We refund you if you fail your exam.

Over 30 million students worldwide already upgrade their learning with 91Ó°ÊÓ!

Key Concepts

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

Radiative Energy
Radiative energy refers to the energy emitted by an object due to its temperature. According to the Stefan-Boltzmann Law, any object emits radiative energy in the form of electromagnetic radiation. This emission is continuous and increases with temperature.

The formula associated with this concept is \[ P = \sigma A T^4 \]where:- \( P \) is the power or radiative energy emitted per unit time,- \( \sigma \) is the Stefan-Boltzmann constant,- \( A \) represents the surface area of the object, and- \( T \) is the object's temperature in Kelvin.

This equation reveals that the power radiated is proportional to the fourth power of the temperature. That means if the temperature doubles, the radiated power increases much more significantly than just doubling. Rather, it becomes 16 times greater due to the fourth power relation.
Kelvin Temperature
The Kelvin temperature scale is an absolute temperature scale used widely in physics. It is set such that 0 Kelvin (0 K) corresponds to absolute zero, the point where molecular motion stops. This makes it ideal for scientific purposes, as it directly correlates with energy levels in a system.

The Kelvin scale avoids negative numbers by starting at absolute zero, making it a perfect fit for equations involving temperature ratios and scientific calculations.

To convert from Celsius to Kelvin, simply add 273.15 to the Celsius temperature. For instance, if the room temperature is 25°C, the Kelvin equivalent would be 298.15 K.

Unlike Celsius or Fahrenheit, the scale's absolute nature ensures it is only equipped for positive values, demonstrating its precise alignment with energy and thermodynamic laws.
Temperature Ratio
The temperature ratio in the context of an object emitting radiative energy is used to compare two different Kelvin temperatures and their respective energy radiations.

When an object's Kelvin temperature changes, the power it emits also changes. Using the Stefan-Boltzmann Law, this can be mathematically represented. Consider the ratio of the emitted power due to temperatures \( T_1 \) and \( T_2 \):\[ \frac{P_2}{P_1} = \left(\frac{T_2}{T_1}\right)^4 \]This indicates that power increases with the fourth power of the temperature increase. In the given exercise, they equate \( P_2 = 2P_1 \), leading to:\[ \left(\frac{T_2}{T_1}\right)^4 = 2 \]Solving this gives the temperature ratio:\[ \frac{T_2}{T_1} = 2^{1/4} \approx 1.189 \]This specific ratio shows how a moderate increase in temperature causes a significant surge in emitted energy.

One App. One Place for Learning.

All the tools & learning materials you need for study success - in one app.

Get started for free

Most popular questions from this chapter

A person is standing outdoors in the shade where the temperature is \(28^{\circ} \mathrm{C} .\) (a) What is the radiant energy absorbed per second by his head when it is covered with hair? The surface area of the hair (assumed to be flat) is 160 \(\mathrm{cm}^{2}\) and its emissivity is \(0.85 (\mathbf {b})\) What would be the radiant energy absorbed per second by the same person if he were bald and the emissivity of his head were 0.65\(?\)

Sirius \(B\) is a white star that has a surface temperature (in kelvins) that is four times that of our sun. Sirius \(\mathrm{B}\) radiates only 0.040 times the power radiated by the sun. Our sun has a radius of \(6.96 \times 10^{8} \mathrm{m} .\) Assuming that Sirius \(\mathrm{B}\) has the same emissivity as the sun, find the radius of Sirius \(\mathrm{B}\) .

How many days does it take for a perfect blackbody cube \((0.0100 \mathrm{m}\) on a side, \(30.0^{\circ} \mathrm{C}\) ) to radiate the same amount of energy that a one hundred-watt light bulb uses in one hour?

Two cylindrical rods have the same mass. One is made of silver (density \(=10500 \mathrm{kg} / \mathrm{m}^{3} )\) , and one is made of iron (density \(=7860 \mathrm{kg} / \mathrm{m}^{3} )\) Both rods conduct the same amount of heat per second when the same temperature difference is maintained across their ends. What is the ratio (silver-to-iron) of \((\mathrm{a})\) the lengths and \((\mathrm{b})\) the radii of these rods?

Multiple-Concept Example 8 reviews the approach that is used in problems such as this. A person eats a dessert that contains 260 Calories. This "Calorie" unit, with a capital \(C,\) is the one used by nutritionists; 1 Calorie \(=4186 \mathrm{J}\) . See Section \(12.7 .\) The skin temperature of this individual is \(36^{\circ} \mathrm{C}\) and that of her environment is \(21^{\circ} \mathrm{C}\) . The emissivity of her skin is 0.75 and its surface area is 1.3 \(\mathrm{m}^{2}\) How much time would it take for her to emit a net radiant energy from her body that is equal to the energy contained in this dessert?

See all solutions

Recommended explanations on Physics Textbooks

View all explanations

What do you think about this solution?

We value your feedback to improve our textbook solutions.

Study anywhere. Anytime. Across all devices.