TOPIC

Statics Section 10 Question 6

 

QUESTION

For the truss shown, determine the forces in members DE and DF, respectively.

A)   500, 0

B)    500, 250

C)    0, 500

D)   0, 0

 

A

C

E

G

H

F

D

B

4

500

500

500

4 panels @ 3ft = 12

HINT

No calculations are necessary. Can you do the problem by inspection?

 

SOLUTION

No calculations are necessary; by inspection both are 0.

Common mistake students make is to assume DE is 500 because of the load at D. Remember each joint must be in equilibrium. If you look at joint E there is nothing balancing the vertical force in DE. Therefore it must be 0.

 

The correct answer is (D)

 

ACKNOWLEDGEMENT

This question of the day was provided by the courtesy of Professor Karim Nohra, a contributor of the Fundamentals of Engineering Examination Question of the Day site at the University of South Florida.