ch01-03 stress & strain & properties
You also want an ePaper? Increase the reach of your titles
YUMPU automatically turns print PDFs into web optimized ePapers that Google loves.
01 Solutions 46060 5/6/10 2:43 PM Page 6<br />
© 2010 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved. This material is protected under all copyright laws as they currently<br />
exist. No portion of this material may be reproduced, in any form or by any means, without permission in writing from the publisher.<br />
1–10. The boom DF of the jib crane and the column DE<br />
have a uniform weight of 50 lb/ft. If the hoist and load weigh<br />
300 lb, determine the resultant internal loadings in the crane<br />
on cross sections through points A, B, and C.<br />
5 ft<br />
D<br />
B<br />
A<br />
2 ft 8 ft 3 ft<br />
F<br />
C<br />
300 lb<br />
7 ft<br />
E<br />
Equations of Equilibrium: For point A<br />
; + © F x = 0; N A = 0<br />
Ans.<br />
+ c © F y = 0; V A - 150 - 300 = 0<br />
V A = 450 lb<br />
Ans.<br />
a +©M A = 0; -M A - 150(1.5) - 300(3) = 0<br />
M A = -1125 lb # ft = -1.125 kip # ft<br />
Ans.<br />
Negative sign indicates that M A<br />
acts in the opposite direction to that shown on FBD.<br />
Equations of Equilibrium: For point B<br />
; + © F x = 0; N B = 0<br />
Ans.<br />
+ c © F y = 0; V B - 550 - 300 = 0<br />
V B = 850 lb<br />
Ans.<br />
a +© M B = 0; -M B - 550(5.5) - 300(11) = 0<br />
M B = -6325 lb # ft = -6.325 kip # ft<br />
Ans.<br />
Negative sign indicates that M B<br />
acts in the opposite direction to that shown on FBD.<br />
Equations of Equilibrium: For point C<br />
; + © F x = 0; V C = 0<br />
Ans.<br />
+ c © F y = 0; -N C - 250 - 650 - 300 = 0<br />
N C = -1200 lb = -1.20 kip<br />
Ans.<br />
a +©M C = 0; -M C - 650(6.5) - 300(13) = 0<br />
M C = -8125 lb # ft = -8.125 kip # ft<br />
Ans.<br />
Negative signs indicate that N C<br />
and M C<br />
act in the opposite direction to that shown<br />
on FBD.<br />
6