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PROBLEM 2.37\n\nKNOWN: Operating data are given for a 10-V battery providing current to resistance.\nFIND: Determine the resistance (R) ohms, and the amount of energy transferred (W) joules.\n\nSCHEMATIC GIVEN DATA: \n10-V \nbattery \nR = 0.5 ohm \nI = 0.2 A\n\nANALYSIS:\nResistance = Voltage/Current = 10 volts / 0.2 A = 50 ohm.\nW = V * I * t (applied to a battery, which is discharging)\nW = (Voltage)(Current)(time) = (10 volts)(0.2 A)(30 min) = 5 watt. \n\nThen, for 30 minutes of operation, \nW = { ∫ Wdt = (5 watt)(30 min) \n= [10^6 J / (60 min)] / [1 watt] = 1.82 x 10^3 J\n\nPROBLEM 2.38\n\nKNOWN: An expression for the power developed by an automobile engine in terms of torque and rotational speed is given.\nFIND: For power in hp, torque in ft-lbf, and rotational speed in RPM, evaluate the values and units of the constants appearing in the given expression.\n\nANALYSIS: The given expression is W = τω / c. When W is in hp, \nτ is ft-lbf and ω is in RPM, by inspection the units of c are [ (ft-lbf)(rev/min) ] / hp.\n\nBeginning with W = J*w, Using equations, we convert .\n W = (J(ft-lbf))(ω(rev/min))\n= | 272.1 | (1 hp) \n | 550 ft-lbf | | 1 rev | (1 hp)\n | 5252 (ft-lbf)(rev/min) | \n\n.: W = C (ft-lbf)(ω(rev/min))\nC = 5252 (ft-lbf)(rev/min) / hp