工程力学吉林大学经典课件.ppt

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1、2023/6/26,Kylinsoft,Statics-Problems-1,第一部分 静力学,2023/6/26,Kylinsoft,Statics-Problems-2,作业题目,作业题目,2023/6/26,Kylinsoft,Statics-Problems-3,P23-1.1(l):,2023/6/26,Kylinsoft,Statics-Problems-4,P23-1.1(g):,2023/6/26,Kylinsoft,Statics-Problems-5,P24-1.2(k):,2023/6/26,Kylinsoft,Statics-Problems-6,P27-1.3(c):

2、,2023/6/26,Kylinsoft,Statics-Problems-7,P27-1.3(e):,2023/6/26,Kylinsoft,Statics-Problems-8,P58-2.3:,Solution:,由此得到如下方程组：,解得：,2023/6/26,Kylinsoft,Statics-Problems-9,P60-2.14:,Solution:,按定义有:,So,expressions(a),(d),(e)are valid.,2023/6/26,Kylinsoft,Statics-Problems-10,P61-2.20:,Solution:,(a),Vector for

3、m:,2023/6/26,Kylinsoft,Statics-Problems-11,(b),Vector form:,2023/6/26,Kylinsoft,Statics-Problems-12,P63-2.28:,+,Solution:,2023/6/26,Kylinsoft,Statics-Problems-13,P63-2.30:,（a),Solution:,2023/6/26,Kylinsoft,Statics-Problems-14,(b),+,2023/6/26,Kylinsoft,Statics-Problems-15,Original forces and couple c

4、an 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,),2023/6/26,Kylinsoft,Statics-Problems-16,P64-2.34:,+,Solution:,2023/6/26,Kylinsoft,Statics-Problems-17,P85-3.2:,Solution:,From the FBD of the beam in Fig:,+,2m,2023/6/26,Kylinsoft,Statics-Pro

5、blems-18,P86-3.11:,Solution:,把人和梯子作为研究对象，作出FBD,(a)x=1.5m,+,2023/6/26,Kylinsoft,Statics-Problems-19,(b),2023/6/26,Kylinsoft,Statics-Problems-20,P87-3.18:,Solution:,0.5m,(1)Studying entire structure,From the FBD of entire structure in Fig:,+,(2)Studying member AB,From the FBD of member AB in Fig:,0.5m

6、,1.6m,+,2023/6/26,Kylinsoft,Statics-Problems-21,(3)Studying member ACE,From the FBD of member ACE in Fig:,0.8m,A,E,C,0.8m,0.6m,0.6m,+,2023/6/26,Kylinsoft,Statics-Problems-22,P90-3.28(f):,Solution:,(1)Studying member CD,From 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,M,C,3m,1m,+,+,2023/

7、6/26,Kylinsoft,Statics-Problems-23,(2)Studying member ABC,A,C,1m,2m,1m,From the FBD of member CD in Fig:,+,+,2023/6/26,Kylinsoft,Statics-Problems-24,P91-3.40:,Solution:,(1)From the FBD of joint A in Fig:,A,1,2,2023/6/26,Kylinsoft,Statics-Problems-25,(2)From the FBD of joint B in Fig:,B,2023/6/26,Kyl

8、insoft,Statics-Problems-26,(3)From the FBD of joint D in Fig:,D,1,2,2023/6/26,Kylinsoft,Statics-Problems-27,(4)From the FBD of joint C in Fig:,C,2023/6/26,Kylinsoft,Statics-Problems-28,P92-3.43:,Solution:,(1)From the FBD of joint D in Fig:,D,(1)From the FBD of joint in Fig:,H,2,3,2023/6/26,Kylinsoft

9、,Statics-Problems-29,P111-4.2:,Solution:,+,+,+,2023/6/26,Kylinsoft,Statics-Problems-30,P113-4.12:,Solution:,From the FBD of bent pipe and cable in Fig:,2023/6/26,Kylinsoft,Statics-Problems-31,无解！？,2023/6/26,Kylinsoft,Statics-Problems-32,P113-4.13:,Solution:,2023/6/26,Kylinsoft,Statics-Problems-33,P1

10、14-4.14(b):,Solution:,S,令形心坐标为(xc,yc),按定义有:,2023/6/26,Kylinsoft,Statics-Problems-34,P115-4.24:,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/m3,O,Studying crucible，Drawing FBD in Fig.,Gi,Gc,+,2023/6/26,Kylinsoft,Statics-Problems-35,2023/6/26,Kylinsoft,Statics-Problems-36,P1

11、16-4.27:,Solution:,x=0,2023/6/26,Kylinsoft,Statics-Problems-37,P131-5.2:,解：,假设系统是静力平衡的,先研究圆柱，有,得,再研究方块，有,得,而,2023/6/26,Kylinsoft,Statics-Problems-38,P132-5.10:,Solution:,总体分析:,分析木条:,圆盘分析:,解之得：,N,f,f,f,C,B,A,.,=22.06,=,=,达到最大静摩擦力时:,解之得：,2023/6/26,Kylinsoft,Statics-Problems-39,P132-5.12:,解：,假设系统是静力平衡的

12、,先研究桩子CBD，有,再研究杆AB，有,2023/6/26,Kylinsoft,Statics-Problems-40,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,2023/6/26,Kylinsoft,Statics-Problems-41,P133-5.18:,Solution:,因此:,2023/6/26,Kylinsoft,Statics-Problems-42,P133-5.19:,Solution:,木块翻转临界时：,滑动时：,2023/6/26,Kylinsoft,Statics-Problems-43,P134-5.22:,当P=600 lb时：,当P=200 lb时：,Solution:,