An exhaust system for a pickup truck is shown in the figure. The weights Wh, Wm, and W₂ of the head-pipe, muffler, and tailpipe are 9, 87, and 41 N, respectively, and act at the indicated points. If the exhaust-pipe hanger at point A is adjusted so that its tensions FA is 69 N, determine the required forces in the hangers at points B, C, and D so that the force-couple system at point O is zero. Why is a zero force-couple system at O desirable? FA FB FC 35° 35° FD WAY B D W = 0.35

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An electric hot water heater consumes 3.1 kilowatts of electricity and converts it to heat. How long will it take the water heater to heat a 67 gallon tank of water from 10 degrees Celsius to 50 degrees Celsius? (1 kilogram of water is 0.37 gallons, 1 Calorie = 4200 J).  It may be helpful to refer back to the weekly handout for guidance on this problem. Your final answer should be in minutes (rounded to the nearest 10 minutes).