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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 .

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.

 





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