MAE 241 - Statics

Summer 2009

Dr. Konstantinos A. SierrosOffice Hours: M and W 10:30 – 11:30 (263 ESB new add)

kostas.sierros@mail.wvu.eduTeaching Blog: http://wvumechanicsonline.blogspot.com

1) Members AC and AB support the 300-lb crate. Determine the tensile force developed in each member.

2) If θ = 45°, determine the moment produced by the 4-kN force about point A.

3. Serious neck injuries can occur when a football player is struck in the face guard of his helmet in the manner shown, giving rise to a guillotine mechanism. Determine the moment of the knee force P = 50 lb about point A.What would be the magnitude of the neck force F so that it gives the counterbalancing moment about A?

4.9 Reduction of a simple distributed loading

• In some cases a body may subjected to a loading that is distributed over its surface• This is called distributed loading• Consider the beam which is subjected to pressure loading that varies only along the x axis• This loading can be described with respect to x

p = p(x) in N/m2

4.9 Reduction of a simple distributed loading

• p = p(x) in N/m2 contains only one variablex and we can represent it as a coplanar distributedload • Therefore, we can multiply the loading functionwith the width b

i.e w(x) = p(x)b in N/m

• We can replace the coplanar force system with aSingle equivalent force FR

Magnitude of FR

Therefore, FR is equal to the total area A under the loading curve

Chapter 5: Equilibrium of a rigid body

Objectives• Develop equations of rigid body equilibrium• Free body diagram for rigid bodies• Solve rigid body equilibrium problems

5.1 Conditions for rigid body equilibrium

FR = ΣF = 0 (MR)o = ΣMo = 0

5.1 Conditions for rigid body equilibrium

Equilibrium in two dimensions

Each wing tire supportsthe same load T

5.2 Free body diagramsSupport reactions

1)

2)

3)