Kenyattta University Large Commercial Nuclear Reactor Questions

I’m working on a physics question and need support to help me learn.

Q # 1 Even when shut down after a period of normal use, a large commercial nuclear reactor produces heat at the rate of 137 MW by the radioactive decay of fission products. This causes a rapid increase in temperature if the cooling system fails.

(a) Calculate the rate of temperature increase in degrees Celsius per second (°C/s), if the mass of the reactor core is 1.60 10⁵ kg and has an average specific heat of 0.0800 kcal/(kg · °C).
°C/s

(b) How long would it take to obtain a temperature increase of 1500°C? (The initial rate of temperature increase would be greater than calculated here, because the heat is concentrated in a smaller mass, but later, the temperature increase would slow because the 5 ✕ 10⁵-kg steel containment vessel would begin to be heated, too.)
s

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Q # 2 Rubbing your hands together warms them by converting work into thermal energy. If a woman rubs her hands back and forth for a total of 18 rubs a distance of 7.50 cm each and with a frictional force averaging 67.3 N, what is the temperature increase? The mass of tissue warmed is only 0.100 kg, mostly in the palms and fingers. The specific heat of the tissue is 3500 J/(kg · °C).
°C

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Q #3 Samantha wishes to maintain her weight and goes to the gym to work off the calories she consumed at breakfast that morning. She lifts a 29.0-kg barbell from shoulder level to above her head, through a vertical height of 0.550 m. How many times must she lift the barbell to make up for the 3.40 10² Calories of energy she consumed at breakfast? Note that Calories refers to food calories. (Include lowering the barbell as well.)
reps

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Q # 4 The “steam” above a freshly made cup of instant coffee is really water vapor droplets condensing after evaporating from the hot coffee. What is the final temperature of 225 g of hot coffee initially at 84.0°C if 5.43 g evaporates from it? The coffee is in a Styrofoam cup, and so other methods of heat transfer can be neglected. Assume that coffee has the same physical properties as water; its latent heat of vaporization is 539 kcal/kg and its specific heat is 1.00 kcal/(kg · °C).
°C

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Q # 5 Radiant heat makes it impossible to stand close to a hot lava flow. Calculate the rate of heat loss by radiation from 1.00 m² of 1200°C fresh lava into 36.2°C surroundings, assuming lava’s emissivity is 1.
kW

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Q # 6 Radiant heat makes it impossible to stand close to a hot lava flow. Calculate the rate of heat loss by radiation from 1.00 m² of 1200°C fresh lava into 36.2°C surroundings, assuming lava’s emissivity is 1.
kW

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Q # 7 Find the net rate of heat loss by radiation from a skier standing in the shade, given the following. She is completely clothed in white (head to foot, including a ski mask), the clothes have an emissivity of 0.200 and a surface temperature of 13.0°C, the surroundings are at −14.3°C, and her surface area is 1.67 m².
W

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Q # 8 Suppose you walk into a sauna that has an ambient temperature of 49.0°C.

(a) Calculate the rate of heat transferred to you by radiation given your skin has a temperature of 37.0°C, an emissivity of 0.98, and the surface area of your body is 1.60 m².
W

(b) If all other forms of heat transfer are balanced (net zero), at what rate will your body temperature increase if your mass is 82 kg? (Assume 3500 J/(kg · °C) is the specific heat of the human body.)

°C/min

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Q # 9 The rate of heat conduction out of a window on a winter day is rapid enough to chill the air next to it. To see just how rapidly windows conduct heat, calculate the rate of conduction in watts through a 2.92 m² window that is 0.595 cm thick if the temperatures of the inner and outer surfaces are 5.00°C and −10.0°C, respectively. This rapid rate will not be maintained — the inner surface will cool, and frost may even form. The thermal conductivity of glass is 0.84 J/(s · m · °C).
W

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Q # 10 Suppose you stand with one foot on ceramic flooring and one on a wool carpet, making contact over a 71.2 cm² area with each foot. Both the ceramic and the carpet are 1.75 cm thick and are 10.0°C on their bottoms. At what rate must each foot supply heat to keep the top of the ceramic and carpet at 33.0°C? The thermal conductivity of ceramic is 0.84 J/(s · m · °C) and that of wool is 0.04 J/(s · m · °C).

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