shi20396_ch01

# shi20396_ch01 - Chapter 1 Problems 1-1 through 1-4 are for...

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Chapter 1 D B G F F acc A E ff 11 u cr u C Impending motion to left F cr Consider force F at G , reactions at B and D . Extend lines of action for fully-developed fric- tion DE and BE to Fnd the point of concurrency at E for impending motion to the left. The critical angle is θ cr . Resolve force F into components F acc and F cr . F is related to mass and acceleration. Pin accelerates to left for any angle 0 <θ<θ cr . When θ>θ cr , no magnitude of F will move the pin. D B G F 9 F 9 acc A E 9? E C d Impending motion to right u 9 F cr 9 u cr 9 Consider force F 0 at G , reactions at A and C . Extend lines of action for fully-developed fric- tion AE 0 and CE 0 to Fnd the point of concurrency at E 0 for impending motion to the left. The critical angle is θ 0 cr . Resolve force F 0 into components F 0 and F 0 cr . F 0 is related to mass and acceleration. Pin accelerates to right for any angle 0 0 0 cr . When θ 0 0 cr , no mag- nitude of F 0 will move the pin. The intent of the question is to get the student to draw and understand the free body in order to recognize what it teaches. The graphic approach accomplishes this quickly. It is im- portant to point out that this understanding enables a mathematical model to be constructed, and that there are two of them. This is the simplest problem in mechanical engineering. Using it is a good way to begin a course. What is the role of pin diameter d ? Yes, changing the sense of F changes the response.

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## shi20396_ch01 - Chapter 1 Problems 1-1 through 1-4 are for...

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