, (. 3.14).
1. , (. 3.14). . . . . , . , . , , . YOZ, , , . (. 3.14):
ΣFZ = 0; P3 P2 + P1 = 7 3 + 5 = 0; = 5 .
, ( . ).
2. , .
3. , . , D.
4. .
. z ( . ) (. 3.14). z 0 1 , .. 0 ≤ z ≤ 1. , . , , .. N. N. N ( ), , , . ( ) :
ΣFZ = 0; + N = 5 + N = 0; N = - 5 .
, N . N z, .
5. , . :
N , (N ) , (N ).
, . N , .. , N , (. 1).
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(. 3.14, . II-II). z . 1 1,5 . , , , II-II N. :
ΣFZ = 0; P3 + N = 5 7 + N = 0; N = 7 5 = 2 .
, (. 3.14).
D.
y |
A |
P3=7 |
P2=3 |
P1=5 |
z |
B |
C |
D |
I |
I |
II |
II |
III |
III |
1 |
0,5 |
0,5 |
z |
) |
=5 |
N |
) |
z |
=5 |
P3=7 |
N |
) |
=5 |
P3=7 |
P2=3 |
N |
) |
z |
N, |
) |
. 3.14.
(. 3.14), , , D . , .
, .
, . ( ). . . I-I (. 3.14) N, , .. ( ). , . , :
N = - = - 5 .
, .
. P3. P3 , , :
N = N + 7 = -5 + 7 = 2 .
. , CD :
NCD = N + 3 = 2 + 3 = 5 .
D P1, :
NCD - P1 = 5 5 = 0,
, .. Σ FZ = 0.
:
1. , , , N, .. .
2. , , , .
3. .
4. , . , , - .
: . , .
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