4.1 .
, , (. 4.1).
, , : , Q N , . , , , . , .
:
1. ( (. 4.1,) ).
2. . , , .
3. , .
4. , 1/3 ÷ 1/4 , M, Q, N. Q, N .
5. , .
4.1 (. 4.2).
1. (. 4.3) , .
Σ mA = 0, - q 5∙2.5 + RB 6 = 0. RB = 6.25 .
Σ m = 0, - q 52.5 - R 6 = 0. R = - 6.25 . R (R = 6,25) .
, , :
Σ mC = 0. RB 4 - HB 5 = 0, HB = 5 .
Σ mC = 0. R 2 + q 5 2.5 HA 5 = 0, HA = 10 .
.
Σ = 0. q 5 - HA - HB = 0.
Σ y = 0. - RA + RB = 0.
2. (. 4.4). , .
, :
3. .
1- , 0 < 1 < 5 .
N 1 = RA = 6.25 .
Q 1 = HA - q∙x 1, Qx= 0 = HA = 10 , Qx= 5 = HA = 10 - 3∙5 = - 5 .
1 = - HA∙x 1 + q∙x 1 ∙x 1/2. . .
= 0 = 0, = 5 = - 10∙5 + 3∙52/2 = - 12,5 ,
= 2,5 = - 10∙2,5 + 3∙(2,5)2/2 = - 15,6 .
2- , 0 < 2 < 6 .
N 1 = - HB = - 5 .
Q 1 = - RB = - 6.25 .
1 = - HB∙ 5 + RB∙x 2. = 0 = - 25 , = 6 = - 25 + 6,25∙6 = 12,5 ,
2- , 0 < 3 < 5 .
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N 1 = - RB = - 6.25 .
Q 1 = HB = 5 .
1 = - HB∙x 3. = 0 = 0, = 5 = - 25 ,
4. (. 4.6)
5. . , (. 4.7). .
4.7 , (Σ = 0, Σ y = 0, Σ m = 0) .
(. 4.8). , .
, , (. ) , . . .
, Q ( +) .
:
Σ = 0. q 5 - HA - HB = 3∙5 10 5 = 0.
Σ y = 0. - RA + RB = - 6,25 + 6,25 = 0.
Σ m A = 0, - q 52.5 + RB 6 = 352.5 6.256 =
= - 37.5 + 37.5 = 0.