Chapter 5 Rigid Body Equilibrium [STATICS]

Equilibrium of a rigid body requires summation of moment to be zero, but at which point?

• Point O only

• Only ONE point

• At ANY point on the body

Match the correct concept of support reactions in preventing motion

[Choose ALL which applicable]

• Preventing TRANSLATION, there is FORCE

• Preventing TRANSLATION, there is MOMENT

• Preventing ROTATION, there is MOMENT

• Preventing ROTATION, there is FORCE

Equations of equilibrium in 2D are

Define sequential procedure to analyse rigid body equilibrium problems

• Apply EoE -> Draw FBD -> Determine all unknowns

• Draw FBD -> Apply EoE -> Determine all unknowns

Tags

NGSS.HS-PS2-1

NGSS.HS-PS2-4

If you got an unknown to be a negative value, what does it mean?

• WRONG solution, RE-DO everything

• CORRECT answer, ACCEPT as it stands

• CORRECT answer, however, the DIRECTION of that force/moment is REVERSED from the assumed

• There is no solution

Tags

NGSS.HS-PS2-4

NGSS.HS-PS2-3

NGSS.HS-PS3-5

Define the concept of TWO-FORCE members

• There are only two forces acting on a member, hence the direction is known, just need to find the magnitude

• There are only two forces acting on a member, need to find both direction and magnitude

In 2D, when a member is a three-force member?

• Concurrent or parallel

• Coplanar

Tags

NGSS.HS-PS2-1

To solve 3D problems, is there any difference with 2D?

• YES, different concept altogether

• NO difference at all

• NO, EXCEPT needs to apply 3D FBD and equilibrium

Match constraints with CORRECT descriptions

[Choose ALL which applicable]

• REDUNDANT constraints: More support than needed for equilbrium

• REDUNDANT constraints: Leads to instability

• REDUNDANT constraints: Statically indeterminate

• IMPROPER constraints: Leads to instability

Tags

NGSS.HS-ETS1-3

NGSS.HS-ETS1-4

Define conditions of rigid body equilbrium