The cable stays AB and AD help support pole AC. Knowing that the tension is 120 lb in AB and 40 lb in AD, determine graphically the magnitude and direction of the resultant of the forces exerted by the stays at A using (a) the parallelogram law, (b) the triangle rule.

CHAPTER 1 CONCEPT OF ENERGY Macroscopic: Things we can see - (Classical Thermodynamics) Microscopic: Statistical Thermodynamics – (Energy being quantized) A Microscopic amount of mass can present energy in the following forms: - Internal – internal structure - Kinetic Energy-Related to motion - Potential Energy-External forces acting on this mass - Rotational Energy-Rotational force TotalEnergy=I+KE+PE+ℜ=U+KE+PE+ℜ Dividingbymassgivesus:e=E /m=u+ke+pe+ℜ=u+1/2v +gh+1/2I ꙍ 2 ¿ Internal Energy (macroscale)-similar set of energies (associated with macroscale motion of individual molecules .U=U external molectranslatio∫molecule Where: U externalmoleculeermolecular forces (PE sum) U translationKE of molecule) U molecul