Zero Force Members

Use the interactive Figure to determine the zero force members in the truss

Use the Figure below to answer the following questions.

For which angle α of force P[sub]a[/sub] does member AB become a zero force member?

180[sup]o[/sup] 0[sup]o[/sup] 90[sup]o[/sup] 45[sup]o[/sup]

For which angle α of force P[sub]a[/sub] does member AG become a zero force member?

45[sup]o[/sup] 90[sup]o[/sup] 75[sup]o[/sup] 180[sup]o[/sup]

For which angle δ of force P[sub]d[/sub], measured clockwise from the horizontal, does member DE become a zero force member?

0[sup]o[/sup] 180[sup]o[/sup] 45[sup]o[/sup] 90[sup]o[/sup]

For which angle δ of force P[sub]d[/sub], measured clockwise from the horizontal, does member DC become a zero force member?

0[sup]o[/sup] 90[sup]o[/sup] 45[sup]o[/sup] 180[sup]o[/sup]

Why is member EC always a zero force member?

Because there is no support reaction at that joint Because it is longer than the other members at the joint Because there is no external force acting on the joint Because it is the third member of a joint where the other two members are collinear

When no external forces act on joint A, members AB and AG are zero force members because?

Because both members are non-collinear Because there is no support reaction at that joint Because there is no external force acting on the joint Because both members are collinear

What following condition is required for member EF to be a zero force member?

When P[sub]c[/sub] is completely vertical (i.e., only has a y-component) Member EF is never a zero force member under any condition When force P[sub]d[/sub] points along member DC (i.e., is collinear with member DC) When force P[sub]d[/sub] is completely horizontal (i.e., only has an x-component)

Which of the following conditions are required for a member to be a zero force member by simple visual inspection? Select all that apply.

When three members form a joint, and two are collinear, the third is a zero force member if an external force or support reaction has a component along that member When three members form a joint, and two are collinear, the third is a zero force member as long as no external force or support reaction has a component along that member When four members form a joint, and two are collinear, the other members are zero force members as long as no external forces or support reactions act along either member When two non-collinear members form a joint, and an external load or support reaction is applied, both members are zero force members When two non-collinear members form a joint, and no external load or support reaction is applied, both members are zero force members

Zero Force Members

Use the interactive Figure to determine the zero force members in the truss

Information: Zero Force Members