A thermos for liquid helium. A physicist uses a cylindrical metal can 0.250 m high and 0.090 m in diameter to store liquid helium at 4.22 K; at that temperature the heat of vaporization of helium is 2.09 × 10 4 J/kg. Completely surrounding the metal can are walls maintained at the temperature of liquid nitrogen, 77.3 K, with vacuum between the can and the surrounding walls. How much helium is lost per hour? The emissivity of the metal can is 0.200. The only heat transfer between the metal can and the surrounding walls is by radiation .
A thermos for liquid helium. A physicist uses a cylindrical metal can 0.250 m high and 0.090 m in diameter to store liquid helium at 4.22 K; at that temperature the heat of vaporization of helium is 2.09 × 10 4 J/kg. Completely surrounding the metal can are walls maintained at the temperature of liquid nitrogen, 77.3 K, with vacuum between the can and the surrounding walls. How much helium is lost per hour? The emissivity of the metal can is 0.200. The only heat transfer between the metal can and the surrounding walls is by radiation .
A thermos for liquid helium. A physicist uses a cylindrical metal can 0.250 m high and 0.090 m in diameter to store liquid helium at 4.22 K; at that temperature the heat of vaporization of helium is 2.09 × 104 J/kg. Completely surrounding the metal can are walls maintained at the temperature of liquid nitrogen, 77.3 K, with vacuum between the can and the surrounding walls. How much helium is lost per hour? The emissivity of the metal can is 0.200. The only heat transfer between the metal can and the surrounding walls is by radiation.
A 6.0-cm-diameter cylinder of nitrogen gas has a 4.0-cm-thick movable copper piston. The
cylinder is oriented vertically, as shown in the figure, and the air above the piston is evacuated.
When the gas temperature is 25 °C, the piston floats 20 cm above the bottom of the cylinder.
(Figure 1)
Figure
20 cm
Vacuum
Piston.
Ź
6 cm
1 of 1
Then 1.5 J of heat energy are transferred to the gas. What is the new equilibrium temperature of the gas in °C?
Express your answer in degrees Celsius.
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T₂ = 115.06992
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Part D
[Π| ΑΣΦ
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What is the final height of the piston?
Express your answer with the appropriate units.
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LO
L₂= 28.05
Part E
6
HÅ
Previous Answers
cm
μÀ
?
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How much work is done on the gas as the piston rises?
Express your answer with the appropriate units.
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?
?
°C
A rectangular window in a home has a length of 1.5 m and a height of 0.80 m. If the window allows heat to escape from the home at a rate of 2,000 watts, how thick must the window be if the inside temperature of the home is 220 C and the outside temperature is 3.00C? (Assume that the coefficient of thermal conduction of glass is 0.80 W/mK.)
a.
7.1 mm
b.
124 mm
c.
9.1 mm
d.
8.1 mm
e.
11 mm
A 200g copper bowl contains 100 g of wate, both at 25 degrees celsius. A very hot 300 g copper cylinder is dropped into the water. The final temperature of the system is 100 degrees celsius. Neglect energy transfer with the environment. The specific heat of water = 4186 J/kg. K and that of copper = 386J/kg. K. How much energy is transferred to the copper bowl as heat?
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