A commonly used packing material consists of \"bubbles\" of air trapped between

Question

A commonly used packing material consists of "bubbles" of air trapped between bonded layers of plastic, explain why this packing material offers less protection on cold days than on warm days. A Goodyear blimp typically contains 5400 m^3 of helium (He) at an absolute pressure of 110000 Pa. The temperature of the helium is 280 K. What is the mass of the helium in the blimp? A bicycle tire whose volume is 0.00041 m^3 has a temperature of 296 K and absolute pressure of 480000 Pa. A cyclist brings the pressure up to 620000 Pa without changing the temperature or volume. How many moles of air must be pumped into the tire? A system does 164 J of work on its environment and gains 77 J of heat in the process. What is the change in internal energy of the system? The input heat for an engine is 2.41 times 10^4 J, and the heat rejected is 5.86 times 10^3 J. What is the work done by the engine? What is the efficiency of the engine?

Explanation / Answer

9) work done = 164 J

heat gained = 77J

dQ = dU + dW

dU = dQ - dW = 77 - 164 = -87 J

10) work done = Qi - Qr

= (2.41 * 10^4 - 5.86*10^3)

= 1.824*10^4 J

efficiency = 1.824*10^4 / 2.4`*10^4 * 100

= 75.68 %

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