可否分享這幾天的高普考題目

[tn002681]

加入土木人討論區粉絲團

請問原點是設在哪??

原點設在c點(0,0,0)

[tn002681]

這題數位學堂有發解答48KN沒錯...另外高考營管第二題
我算的成本差異是..勞務-15750元機具-41250元材料9000元第三題(一)空氣體積0.03m^3、混凝土密度2.33t/m^3 (二)2A=2% 2B=840Kg 2C=97Kg，有人答案跟我一樣嗎?

數位學堂有發解答？我怎麼沒看到？

可以麻煩請這位同學把解答過程po上網嗎？

[tonyliu1104]

哭了，太粗心，普考
第一題 單位力法 積分算錯...
第二題 椼架反力算錯後面全錯....
可以請教有經驗的版友如果觀念都對，答案算錯
大概會怎麼給分呢??

[asasas1234as]

原點設在c點(0,0,0)

-----------------------------------------------------------
如果C是原點 那個點座標應該是
C(0,0,0)
A(6,4,12)
B(10,-2,0)
D(2,10,0)
所以各繩索向量應該是
AC(-6,-4,12)
AB(4,-6,-12)
AD(-4,6,-12)

[opqpk]

工程力學第二題由來 Mechanics of Materials - CengageBrain
★1.2-11 An L-shaped reinforced concrete slab 12 ft  12
ft (but with a 6 ft  6 ft cutout) and thickness t  9.0 in, is
lifted by three cables attached at O, B and D, as shown in
the figure. The cables are combined at point Q, which is
7.0 ft above the top of the slab and directly above the center
of mass at C. Each cable has an effective cross-sectional
area of Ae  0.12 in2
.
(a) Find the tensile force Ti(i  1, 2, 3) in each cable due
to the weight W of the concrete slab (ignore weight of cables).
(b) Find the average stress i in each cable. (See Table
H-1 in Appendix H for the weight density of reinforced
concrete.)