2. A person steps out of the shower and dries off. The person's skin with an emissivity of0.75 has a total area of 1.4m2 and a temperature of 35 Degrees C. What is the powerlost to the room through radiation by the person if the room is 20 Celcius?

Mathematically, the Stefan-Boltzmann Law can be given as, E = σe(T4 - To4) where E is the energy…

Answered: 2. A person steps out of the shower and…

College Physics

10th Edition

ISBN:9781285737027

Author:Raymond A. Serway, Chris Vuille

Publisher:Raymond A. Serway, Chris Vuille

Chapter11: Energy In Thermal Processes

Section: Chapter Questions

Problem 54AP: The surface area of an unclothed person is 1.50 m2, and his skin temperature is 33.0C. The person is...

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A person steps out of the shower and dries off. The person's skin with an emissivity of 0.70 has a total area of 1.2 m and a temperature of 33 °C. What is the net rate at which energy is lost to the room through radiation by the naked person if the room temperature is 24 °C?
5. Calculate the total power radiated per unit area by a tungsten filament at a temperature of 3000. K. (Assume that the filament is an ideal radiator.) (b) If the tungsten filament of a lightbulb is rated at 75.0 W, what is the surface area of the filament? (Assume that the main energy loss is due to radiation.)
Which of the following is NOT an example of a real-life example or application of radiation? A thermos will sometimes have a vacuum layer with no air or other material inside. People who fall into icy water are given shiny, reflective blankets. It's warmer when the lights are on in your home than when they're off. A person Sun-bathing. A thermos flask has a mirrored surface.
A student is trying to decide what to wear.His bedroom is at 20°c.His skin Temperature is 35.0°c.The area of his exposed skin is 1.50 sq.mitres.People all over the world have skin that is dark in the infrared,with emessivity about 0.900.Find the net energy transfer from his body by radiation in 10.0 minutes.
Two stars, A and B, have the same emissivity, but the radii and surface temperatures are different with RA = 0.5RB, and TA = 2TB. Assuming the temperature of space to be negligible, which star radiates the most energy per unit time? a. Star Ab. Star Bc. Both radiate the same amount of energy per unit time.d. More information is needed in order to make a determination.
What is the rate of heat transfer by radiation from the skin of a person standing in a dark room whose ambient temperature is 22 °C ? The person has a normal skin temperature of 33 °C and a surface area of 1.50 m².The emissivity of skin is 0.97 in the infrared, the part of the spectrum where the radiation takes place.
1. A sphere of surface area 100 m and temperature 500 K radiates 0.2 MW. Calculate: a. The emissivity of the surface. b. The peak wavelength of radiation emitted. C. The intensity at a distance of 100m from the centre. d. The energy absorbed per second by a 2m disc with albedo 0.6 placed with it's plane perpendicular to the direction of the radiation. e. The temperature of the disc when it reaches equilibrium (emissivity of the disc = 1). P= eAoT A = 0.00289/T G- 5.67 x 10* Wm°K* Page 1 1 1 Q +
The emissivity of the human skin is 97.0 percent. Use 35.0 °C for the skin temperature and approximate the human body by a rectangular block with a height of 1.77 m, a width of 33.0 cm and a length of 29.5 cm. 1. Calculate the power emitted by the human body. 2. What is the wavelength of the peak in the spectral distribution for this temperature? 3. Fortunately our environment radiates too. The human body absorbs this radiation with an absorbance of 97.0 percent, so we don't lose our internal energy so quickly. How much power do we absorb when we are in a room where the temperature is 26.0 °C? 4. How much energy does our body lose in one second? Please answer all four parts
6. A 2 kg mass is dropped to the ground through a conducting loop. The mass starts 3 meters off the ground with zero velocity, and it lands with a velocity 7 meters/second. You may take g to be 9.8 m/s^2 and ignore all other forces than gravity and electricity + magnetism. How much energy did the conducting loop dissipate (release) as heat and how do you know?
A thin, square steel plate, 10 cm on a side, is heated in a blacksmith's forge to 800°C. If the emissivity is 0.60, what is the total rate of radiation of energy from the plate? A. 800 W B. 600 W C. 450 W D. 900 W
3. The solar constant (Gsc) measured by a scientist is reported as 1385 W/m2. Assume the total hemispherical emissivity is 0.90 on the sun's surface. temperature (in absolute temperature) on sun by using the following information: Estimate the surface Diameter of sun = 1.39 x 10° km Diameter of earth = 1.28 x 10 km Thickness of atmosphere on earth=40 km %3! Average distance between sun and earth = 1.495 x 108 km Suggested reading materials: The chapters regarding "Fundamentals of Thermal Radiation" and "Radiation Exchange between Black Surfaces" in any Heat Transfer textbook.
On a multi-layered square wall, the thermal resistance of the first layer is 0.005 ° C / W, the resistance of the second layer is 0.2 ° C / W, and the third layer is 0.1 ° C / W. The overall temperature gradient in the wall is multilayered from one side. to the other side is 60 ° C. a. Determine the heat flux through the walls. = Answer watts / m2. b. If the thermal resistance of the second layer is changed to 0.3 ° C / W, what is the effect in% on heat flux, assuming the temperature gradient remains the same? = Answer Answer %.

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2. A person steps out of the shower and dries off. The person's skin with an emissivity of 0.75 has a total area of 1.4m2 and a temperature of 35 Degrees C. What is the power lost to the room through radiation by the person if the room is 20 Celcius?