Rates of Heat Transfer
Newton's law of cooling states that the rate of heat loss of a body is directly proportional to the 1 Relationship to mechanism of cooling; 2 Heat transfer version of the law . The heat flow experiences two resistances: the first at the surface of the sphere, and the second within the solid metal (which is influenced by both the. An investigation into the relationship between heat loss and surface area to To investigate this relationship what I did for my preliminary work is to collect six. We make efforts to reduce this heat loss by adding better insulation to walls and attics, . As such, the rate of heat transfer is directly proportional to the surface area the mathematical relationship between these variables and the rate of heat.
And a 40cm3 beaker with 40cm3 of water. I chose these certain volumes for two reasons. Firstly that they are far apart and so will not be similar with each other and have different gradients.
- Investigating the Relationship Between Heat Loss and Surface Area
- An investigation into the relationship between heat loss and surface area to volume ratio
- Rates of Heat Transfer
I will have a thermometer clamped into position half way into the beaker. I will do this because, as I learned from my preliminary work, there are localised heat spots. So if the thermometer is clamped into a secure position these localised heat spots will not make the temperature shown on the thermometer oscillate, as the thermometer will not roll in and out of these hot spots. The safety for the heating procedure is simple. But we must still wear safety goggles and an apron to ensure our eyes remain out of harms way.
How Surface Area affects Heat Transfer. - GCSE Science - Marked by badz.info
I will repeat each experiment 3 times, then average these results and so plot them onto a graph. This will make the data more reliable and the chance of an anomalous result occurring will be significantly reduced. The apparatus will be set up as shown below. I will have to work out the surface area and volume in order to find the surface area to volume ratio. Below is a diagram of a beaker and therefore I will prove why the formula works.
Newton's law of cooling
The first variable is the volume of the water; this is easily controlled by simply measuring out how much water is being used. The localised heat spots are variables as well. To ensure a fair reduction of these heat spots I simply stirred the beaker with the thermometer while I heated. During cooling these localised heat spots will be controlled be keeping the thermometer in one place.
Thus ensuring no accidental contact with the spots which were spread throughout the beaker. The temperature of the surrounding air is another variable. The accumulative effect of the various layers of materials in a window leads to an overall conductivity that is much less than a single pane of uncoated glass.
Lesson 1 of this Thermal Physics chapter has focused on the meaning of temperature and heat. Emphasis has been given to the development of a particle model of materials that is capable of explaining the macroscopic observations.
Efforts have been made to develop solid conceptual understandings of the topic in the absence of mathematical formulas. This solid conceptual understanding will serve you well as you approach Lesson 2. The chapter will turn slightly more mathematical as we investigate the question: Lesson 2 will pertain to the science of calorimetry.
Check Your Understanding 1.
Newton's law of cooling - Wikipedia
Predict the effect of the following variations upon the rate at which heat is transferred through a rectangular object by filling in the blanks. If the area through which heat is transferred is increased by a factor of 2, then the rate of heat transfer is increased by a factor of 2.
If the thickness of the material through which heat is transferred is increased by a factor of 2, then the rate of heat transfer is decreased by a factor of 2.
If the thickness of the material through which heat is transferred is decreased by a factor of 3, then the rate of heat transfer is increased by a factor of 3. If the thermal conductivity of the material through which heat is transferred is increased by a factor of 5, then the rate of heat transfer is increased by a factor of 5.
If the thermal conductivity of the material through which heat is transferred is decreased by a factor of 10, then the rate of heat transfer is decreased by a factor of If the temperature difference on opposite sides of the material through which heat is transferred is increased by a factor of 2, then the rate of heat transfer is increased by a factor of 2.
Use the information on this page to explain why the inch thick layer of blubber on a polar bear helps to keep polar bears warm during frigid artic weather. The blubber has insulating qualities, preventing the escape of heat from the interiors of the polar bear.
The thicker the blubber, the lower the rate of heat transfer. Consider the example problem above. Suppose that the area where the window is located is replaced by a wall with thick insulation. The thermal conductivity of the same area will be decreased to 0. Determine the rate of heat transfer through this area of 2.
How Surface Area affects Heat Transfer.
For example, a Biot number less than 0. This leads to a simple first-order differential equation which describes heat transfer in these systems.
Having a Biot number smaller than 0. The opposite is also true: A Biot number greater than 0. Analytic methods for handling these problems, which may exist for simple geometric shapes and uniform material thermal conductivityare described in the article on the heat equation.
Rate-of-change of temperature-difference version of the law[ edit ] As noted in the section above, accurate formulation for temperatures may require analysis based on changing heat transfer coefficients at different temperatures, a situation frequently found in free-convection situations, and which precludes accurate use of Newton's law.