工程力学吉林大学经典课件.ppt

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1、工程力学吉林大学经典课件 Still waters run deep.流静水深流静水深,人静心深人静心深 Where there is life,there is hope。有生命必有希望。有生命必有希望次数次数 章节章节题目题目一一1(S)P23-1.1(l)(g)、P24-1.2(k)、P27-1.3(c)(e)二二2(S)P58-2.3、P60-2.14、P61-2.20三三2(S)P63-2.28、P63-2.30、P64-2.32、P64-2.34四四3(S)P85-3.2、P86-3.11、P87-3.18、P90-3.28(f)、P91-3.40、P92-3.43五五4(S)P1

2、11-4.2、P113-4.12、P113-4.13 六六4(S)P114-4.14(b)、P115-4.24、P116-4.27七七5(S)P131-5.2、P132-5.12、P133-5.18、P133-5.19、P134-5.22作业题目作业题目作业题目作业题目11/9/2022Statics-Problems-2KylinsoftKylinsoftP23-1.1(l):11/9/2022Statics-Problems-3KylinsoftKylinsoftP23-1.1(g):11/9/2022Statics-Problems-4KylinsoftKylinsoftP24-1.2(

3、k):11/9/2022Statics-Problems-5KylinsoftKylinsoftP27-1.3(c):11/9/2022Statics-Problems-6KylinsoftKylinsoftP27-1.3(e):11/9/2022Statics-Problems-7KylinsoftKylinsoftP58-2.3:Solution:由此得到如下方程组：解得：11/9/2022Statics-Problems-8KylinsoftKylinsoftP60-2.14:Solution:按定义有:So,expressions(a),(d),(e)are valid.11/9/20

4、22Statics-Problems-9KylinsoftKylinsoftP61-2.20:Solution:(a)Vector form:11/9/2022Statics-Problems-10KylinsoftKylinsoft(b)Vector form:11/9/2022Statics-Problems-11KylinsoftKylinsoftP63-2.28:+Solution:11/9/2022Statics-Problems-12KylinsoftKylinsoftP63-2.30:+（a)Solution:11/9/2022Statics-Problems-13Kylinso

5、ftKylinsoft(b)+11/9/2022Statics-Problems-14KylinsoftKylinsoftOOriginal forces and couple can be reduced to a force and a couple acting at point O:P64-2.32:Solution:于是得到合力的大小、方向和作用线位置（如图所示）：(或,或)11/9/2022Statics-Problems-15KylinsoftKylinsoftP64-2.34:+Solution:11/9/2022Statics-Problems-16KylinsoftKyli

6、nsoftP85-3.2:Solution:RAyRByFrom the FBD of the beam in Fig:+RBx3kN2m+11/9/2022Statics-Problems-17KylinsoftKylinsoftP86-3.11:Solution:GPGL把人和梯子作为研究对象，作出FBD(a)x=1.5m+RBRAyRAx+11/9/2022Statics-Problems-18KylinsoftKylinsoft+GPGLRBRAyRAx(b)11/9/2022Statics-Problems-19KylinsoftKylinsoftP87-3.18:Solution:

7、300N0.5mRDRE(1)Studying entire structureFrom the FBD of entire structure in Fig:+(2)Studying member ABFrom the FBD of member AB in Fig:RBxRByRAxRAy300N0.5m1.6m+11/9/2022Statics-Problems-20KylinsoftKylinsoft(3)Studying member ACEFrom the FBD of member ACE in Fig:0.8mRERAxRAyAECRCxRCy0.8m0.6m0.6m+11/9

8、/2022Statics-Problems-21KylinsoftKylinsoftP90-3.28(f):Solution:(1)Studying member CDFrom the FBD of member CD in Fig:显然，本题中在约束A、B、C、D处没有水平方向的作用力RCRMRCR2qC3m1m+11/9/2022Statics-Problems-22KylinsoftKylinsoft(2)Studying member ABCRARCRB2qAC1m2mRARCRB1mFrom the FBD of member CD in Fig:+11/9/2022Statics-

9、Problems-23KylinsoftKylinsoftP91-3.40:Solution:(1)From the FBD of joint A in Fig:APFABFAD12+11/9/2022Statics-Problems-24KylinsoftKylinsoft(2)From the FBD of joint B in Fig:BPFBCFBDFAB+11/9/2022Statics-Problems-25KylinsoftKylinsoft(3)From the FBD of joint D in Fig:DFBD+FDEFADFCD12121211/9/2022Statics

10、-Problems-26KylinsoftKylinsoft(4)From the FBD of joint C in Fig:CRCFCEFBCFCD12+11/9/2022Statics-Problems-27KylinsoftKylinsoftP92-3.43:Solution:(1)From the FBD of joint D in Fig:DPFCDFDH+(1)From the FBD of joint in Fig:HFDHFGFC2323+11/9/2022Statics-Problems-28KylinsoftKylinsoftP111-4.2:Solution:+11/9

11、/2022Statics-Problems-29KylinsoftKylinsoftP113-4.12:Solution:RAzRAyRByRBxRCxRCzFrom the FBD of bent pipe and cable in Fig:11/9/2022Statics-Problems-30KylinsoftKylinsoft无解！？11/9/2022Statics-Problems-31KylinsoftKylinsoftP113-4.13:Solution:11/9/2022Statics-Problems-32KylinsoftKylinsoftP114-4.14(b):Solu

12、tion:S令形心坐标为(xc,yc),按定义有:11/9/2022Statics-Problems-33KylinsoftKylinsoftP115-4.24:Solution:已知crucible的密度rc=2000kg/m3,外径R=0.28m,内径r=0.2m;iron的密度ri=7200kg/m3OStudying crucible，Drawing FBD in Fig.WiWcGiGcFyFx+11/9/2022Statics-Problems-34KylinsoftKylinsoftOWiWcGiGcFyFx11/9/2022Statics-Problems-35Kylinsof

13、tKylinsoftP116-4.27:Solution:x=0 11/9/2022Statics-Problems-36KylinsoftKylinsoftxyO2xyO1P131-5.2:解：3036lb20lb18in假设系统是静力平衡的先研究圆柱，有P1G1G2N1N2f2f1P1得再研究方块，有得而因，所以系统不能保持静力平衡11/9/2022Statics-Problems-37KylinsoftKylinsoftP132-5.10:Solution:总体分析:分析木条:圆盘分析:解之得：解之得：NfffCBA.=22.06=达到最大静摩擦力时:解之得：解之得：11/9/2022S

14、tatics-Problems-38KylinsoftKylinsoft9000N/mBCDBCDP132-5.12:解：P假设系统是静力平衡的先研究桩子CBD，有NBNBNAfAfBRxRy再研究杆AB，有P9000N/m1.5m2m3m0.8mABCDABfBAB11/9/2022Statics-Problems-39KylinsoftKylinsoft只有当fAfAmax或fBfBmax时，杆AB才能移动，由以上计算结果可知，当P6300(N)，杆AB在A点处开始移动11/9/2022Statics-Problems-40KylinsoftKylinsoftP133-5.18:Solution:因此因此:11/9/2022Statics-Problems-41KylinsoftKylinsoftP133-5.19:Solution:木块翻转临界时：滑动时：11/9/2022Statics-Problems-42KylinsoftKylinsoftP134-5.22:当P=600 lb时：当P=200 lb时：Solution:11/9/2022Statics-Problems-43KylinsoftKylinsoft