Mae 241 - Lec7

MAE 241 - Statics Summer 2009

Dr. Konstantinos A. Sierros Office Hours: M and W 10:30 – 11:30 (263 ESB new add) [email protected] Teaching 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 4kN force about point A.

• 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 variable x and we can represent it as a coplanar distributed load • Therefore, we can multiply the loading function with the width b i.e w(x) = p(x)b in N/m • We can replace the coplanar force system with a Single 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 supports the same load T

Support reactions

1) 2)

3)

5.2 Free body diagrams