參考答案:
取起重機考察 ∑M=0 N
×2-P×5-Q×1=0,N
=50kN ∑Y
=0 N
+N
-P-Q=0,N
=10kN 取CD考察 ∑M
0=0 -50×1+R
×8=0,R
=6.25kN ∑Y
=0 6.25-50+Y
=0,Y
=43.75kN ∑X
=0 X
=0 取AC考察,受一平行力系作用 ∑M
=0 R
×4-N′
×7-Y′
×8=0,R
=105kN ∑Y
=0 R
+R
-N′
-Y′
=0,R
=-51.3kN
相關(guān)知識:四、理論力學(xué)