thermo_problems - 100 dB one meter away from a loundspeaker...

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1 Problems . In chapter 20. 4 , 6 , 7 , 20 , 63 , 69 , 77 , 71part a (1) 1. Adiabatic Expansion (a) Starting from dW = pdV show that the work done during an adiabatic expansion is W = 1 γ - 1 [ P 1 V 1 - P 2 V 2 ] (2) where γ is the adiabatic index (b) For an ideal gas expansion explain why dU = nC v dT . Use this to show that Δ U = nC v ( T f - T i ) (3) (c) Show that for an adiabatic expansion Δ U = - W . Show that the expressions given in Eq. 2 and Eq. 3 are consistent with this 2. Internal Combustion Engines: Briefly explain how an internal combustion engine works. Draw a PV cycle. Indicate the different piston strokes work in conjuction with this cycle. Whats the role of the crankshaft and the camshaft? Extra Credit: What are the design constraints of the compression stroke? What are the design constraints of the ignition stroke? 3. Sound 1 At a lound “concert” the band plays close to the threshold of pain. The sound level is
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Unformatted text preview: 100 dB one meter away from a loundspeaker which broadcasts in all directions. (a) Determine determine the sound level 1km away. (b) Is this soft/loud/inaudible? (c) What is the pressure deviation from equilibrium relative to atmospheric pressure (1atm ≈ 1 bar = 10 5 N/m 2 remember!) one meter from the loadspeaker 4. Sound 2 The following picture shows the Pressure measured while beating two frequencies f 1 and f 2 .-2-1.5-1-0.5 0.5 1 1.5 2 2 4 6 8 10 ∆ P time in units of milli sec Beats (a) Estimate from the figure these two frequencies. You may find it convenient to work the next problem first. (b) Show that the sum of two sin waves sin(2 πf 1 t ) and sin(2 πf 2 t ) can be written as a product of sin and cos waves. 1...
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This note was uploaded on 01/25/2012 for the course PHYSICS 141 taught by Professor Teaney during the Fall '10 term at SUNY Stony Brook.

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