Two iron spheres with the same radius look identical from the outside, but one has a hollow cavity on the inside (see below). They are both heated to a temperature of 350° C and suspended by a thin cord from the ceiling of a vacuum chamber. The only way they can lose heat is by radiation. (a) Which sphere, if either, will radiate more watts of power? Explain your answer (b) Which sphere, if either, will cool down the fastest? Explain your answer.
Energy transfer
The flow of energy from one region to another region is referred to as energy transfer. Since energy is quantitative; it must be transferred to a body or a material to work or to heat the system.
Molar Specific Heat
Heat capacity is the amount of heat energy absorbed or released by a chemical substance per the change in temperature of that substance. The change in heat is also called enthalpy. The SI unit of heat capacity is Joules per Kelvin, which is (J K-1)
Thermal Properties of Matter
Thermal energy is described as one of the form of heat energy which flows from one body of higher temperature to the other with the lower temperature when these two bodies are placed in contact to each other. Heat is described as the form of energy which is transferred between the two systems or in between the systems and their surrounding by the virtue of difference in temperature. Calorimetry is that branch of science which helps in measuring the changes which are taking place in the heat energy of a given body.
![**Title: Heat Radiation from Spheres in a Vacuum Chamber**
**Introduction:**
Two iron spheres with the same radius are visually identical from the outside. However, one sphere contains a hollow cavity inside, as demonstrated in the diagrams below. Both spheres are heated to a temperature of 350°C and suspended by thin cords from the ceiling of a vacuum chamber. The only means by which they can lose heat is through radiation.
**Objective:**
This exercise seeks to explore and explain the differences in heat radiation between the two spheres:
1. **Which sphere, if either, radiates more power?**
2. **Which sphere, if either, cools down the fastest?**
Please provide explanations for each answer.
**Diagram Explanation:**
- The upper section of the image shows two iron spheres labeled "a" and "b" hanging from cords.
- The lower section contains an "interior view" for each sphere:
- Sphere "a" shows a cross-section with a hollow cavity.
- Sphere "b" shows a solid cross-section.
**Discussion Points:**
- **Heat Radiation:**
- The rate of radiation depends on the surface area and temperature but not on the volume. Since both spheres have the same outer surface area and are at the same temperature, they will radiate the same amount of power.
- **Cooling Rate:**
- The hollow sphere (sphere "a") has less mass than the solid sphere (sphere "b") due to the absence of material in the cavity. Thus, sphere "a" has less thermal energy to lose and will cool down faster despite radiating the same amount of power per unit time.
Understanding these principles illustrates fundamental concepts of thermodynamics and radiative heat transfer.](/v2/_next/image?url=https%3A%2F%2Fcontent.bartleby.com%2Fqna-images%2Fquestion%2Ff456c65b-f482-4083-8c37-6fe7d8344e1a%2F9f51d51b-6ba2-4ed1-b3ad-0f247ce6ae7b%2Fq4b2kj9_processed.png&w=3840&q=75)
![### Formulas:
#### Specific Heat:
- \( c \equiv \frac{Q}{m \Delta T} \) (J/kg · °C)
- \( Q = mc(T_f - T_i) \)
#### Mixtures:
- \( Q_{\text{cold}} = -Q_{\text{hot}} \)
#### Latent Heat:
- Phase change: \( Q = \pm mL \)
#### Thermal Conductivity:
- \( \frac{Q}{t} = \text{Power} = P = kA\frac{(T_h - T_c)}{L} \)
#### Stefan's Law of Radiation:
- \( P = \sigma A e T^4 \)](/v2/_next/image?url=https%3A%2F%2Fcontent.bartleby.com%2Fqna-images%2Fquestion%2Ff456c65b-f482-4083-8c37-6fe7d8344e1a%2F9f51d51b-6ba2-4ed1-b3ad-0f247ce6ae7b%2Fm80mja_processed.png&w=3840&q=75)
![](/static/compass_v2/shared-icons/check-mark.png)
Step by step
Solved in 2 steps with 1 images
![Blurred answer](/static/compass_v2/solution-images/blurred-answer.jpg)
![College Physics](https://www.bartleby.com/isbn_cover_images/9781305952300/9781305952300_smallCoverImage.gif)
![University Physics (14th Edition)](https://www.bartleby.com/isbn_cover_images/9780133969290/9780133969290_smallCoverImage.gif)
![Introduction To Quantum Mechanics](https://www.bartleby.com/isbn_cover_images/9781107189638/9781107189638_smallCoverImage.jpg)
![College Physics](https://www.bartleby.com/isbn_cover_images/9781305952300/9781305952300_smallCoverImage.gif)
![University Physics (14th Edition)](https://www.bartleby.com/isbn_cover_images/9780133969290/9780133969290_smallCoverImage.gif)
![Introduction To Quantum Mechanics](https://www.bartleby.com/isbn_cover_images/9781107189638/9781107189638_smallCoverImage.jpg)
![Physics for Scientists and Engineers](https://www.bartleby.com/isbn_cover_images/9781337553278/9781337553278_smallCoverImage.gif)
![Lecture- Tutorials for Introductory Astronomy](https://www.bartleby.com/isbn_cover_images/9780321820464/9780321820464_smallCoverImage.gif)
![College Physics: A Strategic Approach (4th Editio…](https://www.bartleby.com/isbn_cover_images/9780134609034/9780134609034_smallCoverImage.gif)