Chapter 18: Problem 6
In which type of process is no work done on a gas? a) isothermal b) isochoric c) isobaric d) none of the above
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An aluminum block of mass \(M_{\mathrm{Al}}=2.0 \mathrm{~kg}\) and specific heat \(C_{\mathrm{Al}}=910 \mathrm{~J} /(\mathrm{kg} \mathrm{K})\) is at an initial temperature of \(1000{ }^{\circ} \mathrm{C}\) and is dropped into a bucket of water. The water has mass \(M_{\mathrm{H}_{2} \mathrm{O}}=12 \mathrm{~kg}\) and specific heat \(C_{\mathrm{H}_{2} \mathrm{O}}=4190 \mathrm{~J} /(\mathrm{kg} \mathrm{K})\) and is at room temperature \(\left(25^{\circ} \mathrm{C}\right) .\) What is the approximate final temperature of the system when it reaches thermal equilibrium? (Neglect heat loss out of the system.) a) \(50^{\circ} \mathrm{C}\) b) \(60^{\circ} \mathrm{C}\) c) \(70^{\circ} \mathrm{C}\) d) \(80^{\circ} \mathrm{C}\)
Which of the following does not radiate heat? a) ice cube b) liquid nitrogen c) liquid helium d) a device at \(T=0.010 \mathrm{~K}\) e) all of the above f) none of the above
The thermal conductivity of fiberglass batting, which is 4.0 in thick, is \(8.0 \cdot 10^{-6} \mathrm{BTU} /\left(\mathrm{ft}^{\circ} \mathrm{F} \mathrm{s}\right) .\) What is the \(R\) value (in \(\left.\mathrm{ft}^{2}{ }^{\circ} \mathrm{F} \mathrm{h} / \mathrm{BTU}\right) ?\)
Assuming the severity of a burn increases as the amount of energy put into the skin increases, which of the following would cause the most severe burn (assume equal masses)? a) water at \(90^{\circ} \mathrm{C}\) b) copper at \(110^{\circ} \mathrm{C}\) c) steam at \(180^{\circ} \mathrm{C}\) d) aluminum at \(100^{\circ} \mathrm{C}\) e) lead at \(100^{\circ} \mathrm{C}\)
Knife blades are often made of hardened carbon steel. The hardening process is a heat treatment in which the blade is first heated to a temperature of \(1346^{\circ} \mathrm{F}\) and then cooled down rapidly by immersing it in a bath of water. To achieve the desired hardness, after heating to \(1346^{\circ} \mathrm{F}\), a blade needs to be brought to a temperature below \(5.00 \cdot 10^{2}{ }^{\circ} \mathrm{F}\). If the blade has a mass of \(0.500 \mathrm{~kg}\) and the water is in an open copper container of mass \(2.000 \mathrm{~kg}\) and sufficiently large volume, what is the minimum quantity of water that needs to be in the container for this hardening process to be successful? Assume the blade is not in direct mechanical (and thus thermal) contact with the container, and neglect cooling through radiation into the air. Assume no water boils but reaches \(100^{\circ} \mathrm{C} .\) The heat capacity of copper around room temperature is \(c_{\text {copper }}=386 \mathrm{~J} /(\mathrm{kg} \mathrm{K}) .\) Use the data in the table below for the heat capacity of carbon steel
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