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EGR_102_Lecture_HW_01

# EGR_102_Lecture_HW_01 - The volume flow rate through a pipe...

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EGR 102 of 4 pages Lecture HW 01 1 EGR 102 Lecture HW 01 Due at beginning of lecture on Friday, January 21 4 Problems, 3 Points Each Name: PID: Problem 1 (3 pts): A group of 30 students attend a class in a room that measures 10m by 8m by 3m. Each student takes up 0.075 m 3 and gives out 80W of heat (1W = 1 J/s). Calculate the air temperature rise during the first 15 minutes of the class if the room is completely sealed and insulated. Assume heat capacity, C v , for air is 0.718 kJ/(kg K). Assume air is an ideal gas at 20°C and 101.325 kPa. Note that the heat absorbed by the air Q is related to the mass of the air m , the heat capacity, and the change in temperature by the following relationship: Q = mC v (T 2 -T 1 ) The mass of the air can be obtained from the ideal gas law: PV = mRT / Mwt Where P is the gas pressure, V is the volume of the gas, Mwt is the molecular weight of the gas (for air, 28.97 kg/kmol), and R is the ideal gas constant [8.314 kPa m 3 /(kmol K)].

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EGR 102 of 4 pages Lecture HW 01 2 Problem 2 (3 pts):

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Unformatted text preview: The volume flow rate through a pipe is given by Q = vA , where v is the average velocity and A is the cross-sectional area. Use volume-continuity to solve for the required area in pipe 3. EGR 102 of 4 pages Lecture HW 01 3 Problem 3 (3 pts): For the free-falling parachutist with linear drag, assume a first jumper is 70 kg and has a drag coefficient of 12 kg/s. If a second jumper has a drag coefficient of 15 kg/s and a mass of 75 kg, how long will it take him to reach the same velocity the first jumper reached in 10 s? EGR 102 of 4 pages Lecture HW 01 4 Problem 4 (3 pts): Compute the velocity of a free-falling parachutist using Euler’s method for the case where m = 80 kg and c d = 10 kg/s. Perform the calculation from t = 0 to 20 s with step size of 1 s. Use an initial condition that the parachutist has an upward velocity of 20 m/s at t = 0. At t = 10 s, assume that the chute is instantaneously deployed so that the drag coefficient jumps to 50 kg/s....
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EGR_102_Lecture_HW_01 - The volume flow rate through a pipe...

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