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About
http://weelookang.blogspot.sg/2014/11/ejss-cube-block-cooling-model.html
image of
copper shiny https://c1.staticflickr.com/1/164/362133253_77585f5429_z.jpg?zz=1
copper dull https://www.colourbox.com/preview/10760507-196481-golden-copper-shiny-abstract-vertical-background.jpg
al shiny http://preview.cutcaster.com/cutcaster-photo-100709683-metal-texture.jpg
al dull http://pixabay.com/p-432524/?no_redirect
fe shiny http://www.burningwell.org/gallery2/d/11247-6/img_0571.jpg
fe dull http://upload.wikimedia.org/wikipedia/commons/1/1d/Old_dirty_dusty_rusty_scratched_metal_iron.jpg
Translations
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Software Requirements
| Android | iOS | Windows | MacOS | |
| with best with | Chrome | Chrome | Chrome | Chrome |
| support full-screen? | Yes. Chrome/Opera No. Firefox/ Samsung Internet | Not yet | Yes | Yes |
| cannot work on | some mobile browser that don't understand JavaScript such as..... | cannot work on Internet Explorer 9 and below |
Credits
This email address is being protected from spambots. You need JavaScript enabled to view it.; christian wolfgang
end faq
Sample Learning Goals
Shiny or Dull bug fixed
Title: Block Mass 0.1 kg Cooling and Heating Curve with Different Materials and Surface Area Model
Introduction:
In this blog post, we will explore the cooling and heating curves of a block with a mass of 0.1 kg, focusing on the influence of different materials and surface area on the temperature changes. Understanding these factors is crucial for various applications, from designing efficient cooling systems to optimizing heating processes. So, let's dive into the fascinating world of thermal dynamics!
The Basics of Cooling and Heating Curves:
Before we delve into the specifics, let's briefly explain what cooling and heating curves represent. A cooling curve illustrates how the temperature of an object changes over time as it loses heat to its surroundings. Conversely, a heating curve shows the temperature changes as the object gains heat from its surroundings. Both curves typically display a gradual decrease or increase in temperature, eventually reaching a state of equilibrium.
Exploring Shiny or Dull:
When exploring different surface types, such as shiny and dull, we encounter distinct characteristics that influence their interaction with heat and light. Shiny surfaces, characterized by a smooth and reflective texture, have the ability to reflect a significant portion of incoming radiation, including heat. As a result, shiny surfaces tend to absorb less heat energy, leading to slower temperature increases. Conversely, dull surfaces, with their rough and non-reflective texture, have lower reflectivity and greater capacity to absorb radiation. This absorption promotes the retention of heat energy, causing dull surfaces to heat up faster compared to their shiny counterparts. The reflective properties of shiny surfaces and the absorptive properties of dull surfaces highlight the importance of surface characteristics when considering heat transfer and temperature changes.
Exploring Different Materials:
The choice of material significantly affects the cooling and heating behavior of an object.
When both blocks are exposed to a colder environment, such as a room at a lower temperature, the metal block will cool down faster than the wooden block. Metals generally have higher thermal conductivity, allowing heat to transfer more rapidly from the block's surface into the surrounding air. Wood, on the other hand, has lower thermal conductivity, resulting in a slower cooling process.
Conversely, when both blocks are subjected to a hotter environment, such as a heat source, the metal block will heat up faster than the wooden block. Metals again exhibit higher thermal conductivity, enabling them to absorb and distribute heat more efficiently.
Examining Surface Area:
In addition to material properties, the surface area of an object also plays a crucial role in its cooling and heating rates. To observe this effect, let's consider two blocks made of the same material, both with a mass of 0.1 kg, but with different surface areas.
If we compare a larger block with a larger surface area to a smaller block with a smaller surface area, both exposed to the same cooling or heating conditions, the larger block will experience faster temperature changes. This is because the larger surface area provides more space for heat exchange with the surroundings, promoting quicker heat transfer and resulting in a more rapid cooling or heating process.
Conclusion:
Understanding the cooling and heating curves of objects is essential for numerous real-world applications. In this blog post, we explored how different materials and surface areas can influence the temperature changes of a 0.1 kg block. Metals generally exhibit higher thermal conductivity, leading to faster heat transfer and thus quicker cooling and heating. Additionally, objects with larger surface areas experience more rapid temperature changes due to increased heat exchange with the surroundings.
By considering these factors, engineers and scientists can design more efficient cooling and heating systems, optimize thermal processes, and make informed decisions in various industries. So, next time you encounter a cooling or heating challenge, remember the influence of materials and surface area on the fascinating world of thermal dynamics!
SLS Lesson by Kong Su Sze
Good conductors of heat
steel, copper
Poor conductors of heat
plastic, wood
Answer Key
For Teachers
Newton's Law of Cooling
The Newton's Law of Cooling model computes the temperature of an object of mass M as it is heated or cooled by the surrounding medium.
Assumption:
Validity:
Convection-cooling "Newton's law of cooling" Model:
\( T_{background} \) is the temperature of the surrounding background environment; i.e. the temperature suitably far from the surface is the time-dependent thermal gradient between environment and object.
Definition Specific Heat Capacity:
The specific heat capacity of a material on a per mass basis is\( m \) is the mass of the body
\( c \) specific heat capacity of a material
\( T_{final} \) is the \(T_{background}\)
\( T_{initial}\) is the \( T(t) \)
\( \frac{mc ( T_{background}- T(t) ) }{\delta t} = h A( T(t) - T_{background} )\)
assuming mc is constant'
\( mc \frac{ \delta ( T_{background}- T(t) ) }{\delta t} = h A( T(t) - T_{background} )\)
\( \frac{ ( T_{background}) }{\delta t} = 0 \)
negative sign can be taken out of the differential equation.
\( \frac{ ( T(t) ) }{\delta t} = -\kappa ( T(t) - T_{background} )\)
If heating is added on,
the final ODE equation looks like
Definition Equation Used:
\( V \) is volume of object
\( \rho \) is density of object
\( A \) surface area of object
assumption of increased surface are
Materials added:
copper shiny \( c_{Cu} \) = 385 \( \frac{J}{kg K}\)\( \rho_{Cu} \) = 8933 \( \frac{kg}{m^{3}}\)
heat transfer coefficient \(h_{Cu}\) = 400 \( \frac{W}{(K m^{2})} \)
copper dull \( c_{Cu} \) = 385 \( \frac{J}{kg K}\)
\( \rho_{Cu} \) = 8933 \( \frac{kg}{m^{3}}\)
heat transfer coefficient \(h_{Cu}\) = 200 \( \frac{W}{(K m^{2})} \)
aluminium shiny \( c_{Al} \) = 903 \( \frac{J}{kg K}\)
\( \rho_{Al} \) = 2702 \( \frac{kg}{m^{3}}\)
heat transfer coefficient \(h_{Al}\) = 400 \( \frac{W}{(K m^{2})} \)
aluminium dull \( c_{Al} \) = 903 \( \frac{J}{kg K}\)
\( \rho_{Al} \) = 2702 \( \frac{kg}{m^{3}}\)
heat transfer coefficient \(h_{Al}\) = 200 \( \frac{W}{(K m^{2})} \)
iron shiny \( c_{Al} \) = 447 \( \frac{J}{kg K}\)
\( \rho_{Al} \) = 7870 \( \frac{kg}{m^{3}}\)
heat transfer coefficient \(h_{Al}\) = 400 \( \frac{W}{(K m^{2})} \)
iron dull \( c_{Al} \) = 447 \( \frac{J}{kg K}\)
\( \rho_{Al} \) = 7870 \( \frac{kg}{m^{3}}\)
heat transfer coefficient \(h_{Al}\) = 200 \( \frac{W}{(K m^{2})} \)
Users can select the mass of the object and the material and the model computes the surface area assuming a cubic shape. The model plots the object's temperature as a function of time as the user heats and cools the object. A data-tool button on the temperature graph allows users fit the data to analytic functions.
Note: A typical (rough) heat transfer coefficient h for still air and iron is 6 W/(K m^2) and 400 W/(K m^2) . The Newton's Law of Cooling model assumes h=400 for all shiny and h=200 for dull materials. The actual value of h depends on many parameters including the material, the fluid velocity, the fluid viscosity and the condition of the object's surface.
References:
- "Measuring the Specific Heat of Metals by Cooling," William Dittrich, The Physics Teacher, (in press).
Credits:
- The Newton's Law of Cooling model was created by Wolfgang Christian using the Easy Java Simulations (EJS) version 4.2 authoring and modeling tool.
- EJSS Cube Block Cooling Model was created by Wolfgang Christian and recreated by lookang using the Easy Java Simulations (EJS) version 5.1 authoring and modeling tool
Research
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Video
https://www.youtube.com/watch?v=8a8nTQIdLOM
Version:
- http://weelookang.blogspot.sg/2014/11/ejss-cube-block-cooling-model.html
- https://vle.learning.moe.edu.sg/community-gallery/lesson/view/5d907c47-4ae6-47e7-8cce-04199b1cd386
- https://weelookang.blogspot.com/2023/05/block-mass-01-kg-cooling-and-heating.html
Hands-On Kits
- http://www.addest.com/products/category/Science_Kits by Addest Station
Cooling Curve Kit
Other Resources
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