工程力学吉林大学经典课件.ppt
2019/3/30,Kylinsoft,Statics-Problems-1,第一部分 静力学,2019/3/30,Kylinsoft,Statics-Problems-2,作业题目,作业题目,2019/3/30,Kylinsoft,Statics-Problems-3,P23-1.1(l):,2019/3/30,Kylinsoft,Statics-Problems-4,P23-1.1(g):,2019/3/30,Kylinsoft,Statics-Problems-5,P24-1.2(k):,2019/3/30,Kylinsoft,Statics-Problems-6,P27-1.3(c):,2019/3/30,Kylinsoft,Statics-Problems-7,P27-1.3(e):,2019/3/30,Kylinsoft,Statics-Problems-8,P58-2.3:,Solution:,由此得到如下方程组：,解得：,2019/3/30,Kylinsoft,Statics-Problems-9,P60-2.14:,Solution:,按定义有:,So, expressions (a), (d), (e) are valid.,2019/3/30,Kylinsoft,Statics-Problems-10,P61-2.20:,Solution:,(a),Vector form:,2019/3/30,Kylinsoft,Statics-Problems-11,(b),Vector form:,2019/3/30,Kylinsoft,Statics-Problems-12,P63-2.28:,+,Solution:,2019/3/30,Kylinsoft,Statics-Problems-13,P63 -2.30:,（a),Solution:,2019/3/30,Kylinsoft,Statics-Problems-14,(b),+,2019/3/30,Kylinsoft,Statics-Problems-15,Original 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,),2019/3/30,Kylinsoft,Statics-Problems-16,P64-2.34:,+,Solution:,2019/3/30,Kylinsoft,Statics-Problems-17,P85-3.2:,Solution:,From the FBD of the beam in Fig:,+,2m,2019/3/30,Kylinsoft,Statics-Problems-18,P86-3.11:,Solution:,把人和梯子作为研究对象，作出FBD,(a) x=1.5m,+,2019/3/30,Kylinsoft,Statics-Problems-19,(b),2019/3/30,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,1.6m,+,2019/3/30,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,+,2019/3/30,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,+,+,2019/3/30,Kylinsoft,Statics-Problems-23,(2) Studying member ABC,A,C,1m,2m,1m,From the FBD of member CD in Fig:,+,+,2019/3/30,Kylinsoft,Statics-Problems-24,P91-3.40:,Solution:,(1) From the FBD of joint A in Fig:,A,1,2,2019/3/30,Kylinsoft,Statics-Problems-25,(2) From the FBD of joint B in Fig:,B,2019/3/30,Kylinsoft,Statics-Problems-26,(3) From the FBD of joint D in Fig:,D,1,2,2019/3/30,Kylinsoft,Statics-Problems-27,(4) From the FBD of joint C in Fig:,C,2019/3/30,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,2,3,2019/3/30,Kylinsoft,Statics-Problems-29,P111-4. 2:,Solution:,+,+,+,2019/3/30,Kylinsoft,Statics-Problems-30,P113-4.12:,Solution:,From the FBD of bent pipe and cable in Fig:,2019/3/30,Kylinsoft,Statics-Problems-31,无解！？,2019/3/30,Kylinsoft,Statics-Problems-32,P113-4.13:,Solution:,2019/3/30,Kylinsoft,Statics-Problems-33,P114-4.14(b):,Solution:,S,令形心坐标为(xc, yc), 按定义有:,2019/3/30,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,+,2019/3/30,Kylinsoft,Statics-Problems-35,2019/3/30,Kylinsoft,Statics-Problems-36,P116-4.27:,Solution:,x=0,2019/3/30,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,2019/3/30,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：,2019/3/30,Kylinsoft,Statics-Problems-39,P132-5.12:,解：,假设系统是静力平衡的,先研究桩子CBD，有,再研究杆AB，有,2019/3/30,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,2019/3/30,Kylinsoft,Statics-Problems-41,P133-5.18:,Solution:,因此 :,2019/3/30,Kylinsoft,Statics-Problems-42,P133-5.19:,Solution:,木块翻转临界时：,滑动时：,2019/3/30,Kylinsoft,Statics-Problems-43,P134-5.22:,当P=600 lb时：,当P=200 lb时：,Solution:,
