课程名称︰静力学 课程性质︰必修 课程教师︰陈国在 开课学院：工学院 开课系所︰工科海洋系 考试日期（年月日）︰2012/04/19 考试时限（分钟）：120分钟 是否需发放奖励金：是 试题: Problem 1: answer the following questions: 1. What is the difference of a free vector from a sliding vector?(5%) 2.For some concurrent forces at point O in a plane, try to show the simplest resultant for them.(5%) 3.If the forces system in question 2 is in equilibrium, what is its equation of equilibrium?(5%) 4.Try to write all possible sets of equilibrium equation for a general plane planes system.(5%) Problem 2: The rigid pole and cross-arm assembly is supported by the three cables shown. Determine the vector expression for the monent of the 1.2-kN tension (a) about point B and about the pole z-axis (15%). Problem 3: As discussed in the text and classroom, the equations of equilibrium for a plane mechanical forces system is usually two force equations and one moment equation. Try to prove that the above three equations by three moment equations (14%). Problem 4: Determine the wrench resultant of the three forces acting on the bracket. Calculate the coordinates of the point in the x-y plane through which the resultant force of the wrench acts. Also find the magnitude of the couple M of the wrench (14%). Problem 5: Determine the tension T in the turnbuckle for the pulley-cable system in terms of the mass m of the body which it supports. Here the mass of the pulleys and cable are neglected. Problem 6: What is the degree of the statical indetrminancy for a mechanical system in equilibrium? And also count the degree of statical indeterminancy for a plane beam in both-ends built-in support(14%). Problem 7: As talked in classroom, the free-body diagram of a mechanical system plays the most important role in setting up the equations of equilibrium for the system. Can you tell the sense of the free-body diagram of a mechanical system? Again try to draw it for the system ] as shown in Fig. 3/2.3(14%). --

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