解题思路:
(1)人受到重力、支持力和绳子的拉力,
有:
M
g
=
N
+
T
T
=
m
g
解得
N
=
M
g
−
T
=
M
g
−
m
g
=
200
N
.
(2)
BO
绳的拉力
T
′
=
2
T
=
2
mg
=
600
N
,
根据共点力平衡得:
F
A
B
=
=
400
N
.
F
B
C
=
F
A
B
sin
30
∘
=
200
N
.
(1)200N (2)200
N
<>
解题思路:
(1)人受到重力、支持力和绳子的拉力,
有:
M
g
=
N
+
T
T
=
m
g
解得
N
=
M
g
−
T
=
M
g
−
m
g
=
200
N
.
(2)
BO
绳的拉力
T
′
=
2
T
=
2
mg
=
600
N
,
根据共点力平衡得:
F
A
B
=
=
400
N
.
F
B
C
=
F
A
B
sin
30
∘
=
200
N
.
(1)200N (2)200
N
<>