12-100ex1 - What percentage of logs, out of the whole...

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12-100 22 February 2008 Exam 1 Appropriate free body diagrams must accompany all calculations involving static equilibrium. Use three significant figures in all calculations. 1. You run a sawmill where you saw logs into planks, and you receive a large batch of logs in which the length is a normally distributed random variable with a mean of 35 ft. When you start processing this batch you first set aside all logs longer than 48 ft because you will sell them as telephone poles, not as planks; you observe that 18% of the logs fall into the telephone pole category. You next remove all logs shorter than 16 ft because they are too short to make good planks, and instead you will use them for plywood.
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Unformatted text preview: What percentage of logs, out of the whole batch, are too short to be made into planks? [30 pts] 2. Frame ABCD is supported by a hinged support at A and by a roller on a horizontal surface at D, and carries a 1500 lb load as shown at C. Determine the reaction components at A and D. When you are done, you must sketch a new free body diagram showing all the forces acting on frame ABCD, with their proper physical magnitude and direction. [35 pts] 3. A beam spans 16 ft and carries a 1000 lb force at midspan. The wood has an allowable bending stress of 1500 lb/in 2 ; the beam is to be 4 in deep, and you must choose its width dimension, b. [35 pts]...
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12-100ex1 - What percentage of logs, out of the whole...

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