1.) The tip of a cigarette often becomes %26quot;red hot%26quot; when a smoker inhales. Using the relation between dominant wavelength and temperature for an ideal radiator, estimate the cigarette tip temperature knowing that red color has a wavelength of about 0.65 micrometer.
2.) An object at room temperature radiates energy at a rate of about 0.3 watts per square inch of surface. The human body has about 2800 square inches of surface area.What is the rate of emission of energy byt the human body at room temperature? How does this rate of emission compare with a typical light bulb?
3.) How does a temperature change 1 degree Celsius compare with a temperature of 1 degree Farenheit? How does a temperature change of 1 degree Celsius compare with a temperature change of 1 K?
4.) Very few substances have a higher specific heat than water. Consequently, water is useful for cooling the condensor of a steam turbine. To show why, determine the temperature rise of one kilogram of water and one kilogram of copper if each absorbs 1000 joules of heat. Water = 1.00 calories/gram Celsius and copper = 0.093 calories/ gram Celsius.
5.) A 1000-kilogram concrete pillar in a house stores thermal energy it acquires from sunlight entering through windows. The temperature of the pillar rises to 30 degrees Celsius on a bright, sunny day.
a.) How many calories of thermal energy are available from this pillar when it cools to 24 degrees Celsius .....Concrete = 0.22 calories/ gram Celsius
b.) If the nightly heat requirement to maintain the house at 24 degrees Celsius is 7 million calories, what fraction of the heat load could be provided by the concrete?Can someone please help me with my physics presentation?1. This problem makes me feel nauseous thinking about cigarrettes
use Wien's law, with wavelength:
lambda*T = 2898 microns-K
solve for T:
T = 4458 Kelvin
Comment: red probably isn't the dominant color if it only appears red. An incandescent filament is at T = 2600 Kelvin, and it appears mainly white. There is more to the story that they aren't telling you.
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2. This question doesn't make much sense, but I know the typical figure is that humans dissipate is 100 watts of heat.
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3. A change of 1 Celsius is 9/5 times as large as a change of 1 Farenheit. A change of 1 Celsius is the same as 1 Kelvin, in fact, the Kelvin scale is defined so this is true.
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4. 1000 Joules = 238.846 calories.
Q = m*c*deltaT
1 kg of Water will rise by 0.239 Celsius
1 kg of Cu will rise by 2.57 Celsius
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5) Q = m*c*deltaT
Q = (1e6 g)*(0.22 cal/g-C)*(6 C)
A:
Q = 132 MegaCalories
B:
This pillar provides enough heat for 18 evenings. However, due to heat transfer to the outside air, it will not actually do this. You will find only a tiny fraction of the 132 megacalories actually makes it in to the house.
