chapter 13
3–1.
The members of a truss are pin connected at joint O.
Determine the magnitudes of F1 and F2 for equilibrium.
Set u = 60°.
y
5 kN
F2
70Њ
30Њ
x
SOLUTION
+
: ©Fx = 0;
O
F2 sin 70° + F1 cos 60° - 5 cos 30° -
4
(7) = 0
5
5
3
4
0.9397F2 + 0.5F1 = 9.930
7 kN
+ c ©Fy = 0;
u
3
F2 cos 70° + 5 sin 30° - F1 sin 60° - (7) = 0
5
F1
Solving:
T an his th d wo sa eir is p rk w le co ro is ill o u vi pr de f a rse de ot st ny s d s ec ro p an o te y ar d le d th t o a ly by e s in f th se for Un te is ss th ite gr w in e ity o g us d S of rk ( stu e o tat th inc de f i es e lu nt ns co w d le tr p or in a uc y k g rn to rig an on in rs h d th g. in t la is e D t w no W iss ea s t p or em ch in er ld m W ina g itt id tio ed e n
. We or
b)
0.3420F2 - 0.8660F1 = 1.7
F2 = 9.60 kN
Ans.
F1 = 1.83 kN
Ans.
© 2013 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved. This publication is protected by
Copyright and written permission should be obtained from the publisher prior to any prohibited reproduction, storage in a retrieval system, or transmission in any form or by any means, electronic, mechanical, photocopying, recording, or likewise. For information regarding permission(s), write to:
Rights and Permissions Department, Pearson Education, Inc., Upper Saddle River, NJ 07458.
3–2.
The members of a truss are pin connected at joint O.
Determine the magnitude of F1 and its angle u for equilibrium. Set F2 = 6 kN.
y
5 kN
F2
70Њ
30Њ
x
SOLUTION
+
: ©Fx = 0;
O
6 sin 70° + F1 cos u - 5 cos 30° -
4
(7) = 0
5
5
F1 cos u = 4.2920
+ c ©Fy = 0;
6 cos 70° + 5 sin 30° - F1 sin u -
u
3
4
3
(7) = 0
5
7 kN
F1
F1 sin u = 0.3521
Solving:
Ans.
F1 = 4.31 kN
Ans.
T an his th d wo sa eir is p rk w le co ro is ill o u vi pr de f a rse de ot st ny s d s ec ro p an o te y ar d le d th t o a ly by
The members of a truss are pin connected at joint O.
Determine the magnitudes of F1 and F2 for equilibrium.
Set u = 60°.
y
5 kN
F2
70Њ
30Њ
x
SOLUTION
+
: ©Fx = 0;
O
F2 sin 70° + F1 cos 60° - 5 cos 30° -
4
(7) = 0
5
5
3
4
0.9397F2 + 0.5F1 = 9.930
7 kN
+ c ©Fy = 0;
u
3
F2 cos 70° + 5 sin 30° - F1 sin 60° - (7) = 0
5
F1
Solving:
T an his th d wo sa eir is p rk w le co ro is ill o u vi pr de f a rse de ot st ny s d s ec ro p an o te y ar d le d th t o a ly by e s in f th se for Un te is ss th ite gr w in e ity o g us d S of rk ( stu e o tat th inc de f i es e lu nt ns co w d le tr p or in a uc y k g rn to rig an on in rs h d th g. in t la is e D t w no W iss ea s t p or em ch in er ld m W ina g itt id tio ed e n
. We or
b)
0.3420F2 - 0.8660F1 = 1.7
F2 = 9.60 kN
Ans.
F1 = 1.83 kN
Ans.
© 2013 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved. This publication is protected by
Copyright and written permission should be obtained from the publisher prior to any prohibited reproduction, storage in a retrieval system, or transmission in any form or by any means, electronic, mechanical, photocopying, recording, or likewise. For information regarding permission(s), write to:
Rights and Permissions Department, Pearson Education, Inc., Upper Saddle River, NJ 07458.
3–2.
The members of a truss are pin connected at joint O.
Determine the magnitude of F1 and its angle u for equilibrium. Set F2 = 6 kN.
y
5 kN
F2
70Њ
30Њ
x
SOLUTION
+
: ©Fx = 0;
O
6 sin 70° + F1 cos u - 5 cos 30° -
4
(7) = 0
5
5
F1 cos u = 4.2920
+ c ©Fy = 0;
6 cos 70° + 5 sin 30° - F1 sin u -
u
3
4
3
(7) = 0
5
7 kN
F1
F1 sin u = 0.3521
Solving:
Ans.
F1 = 4.31 kN
Ans.
T an his th d wo sa eir is p rk w le co ro is ill o u vi pr de f a rse de ot st ny s d s ec ro p an o te y ar d le d th t o a ly by