美国麻省理工大学：《Aerospace Dynamics（航空动力学）》英文版 lecture 11

Spring 2003 Generalized forces revisited Derived Lagrange s equation from d'Alembert's equation ∑m(8x+16y+22)=∑(Fx+F+F。=) Define virtual displacements sx Substitute in and noting the independence of the 8q,, for each

Spring 2003 Derivation of lagrangian equations Basic Concept: Virtual Work Consider system of N particles located at(, x2, x,,.x3N )with 3 forces per particle(f. f, f..fn). each in the positive direction

Spring 2003 Example Given: Catapult rotating at a constant rate(frictionless, in the horizontal plane) Find the eom of the particle as it leaves the tube

NUMERICAL SOLUTION GIEN A COMPLEX SET of OYNAMICS (t)=F(x) WHERE F() COULD BE A NONLINEAR FUNCTION IT CAN BE IMPOSS IBLE To ACTVALLY SOLVE FoR ( ExACTLY. OEVELOP A NUMERICAL SOLUTION. CANNED CoDES HELP US THIS TN MATLAB BUT LET US CONSDER THE BASiCS

Introduction We started with one frame (B) rotating and accelerating with respect to another(), and obtained the following expression for the absolute acceleration

Spring 2003 Lagrange's equations Joseph-Louis lagrange 1736-1813 http://www-groups.dcs.st-and.ac.uk/-history/mathematicians/lagranGe.html Born in Italy. later lived in berlin and paris Originally studied to be a lawyer Interest in math from reading halleys 1693 work on

CoRIoLIS ACcELERAT0 EMYSTIF∈p CONSIOER CASE oF CONSTANT ROTA ToN.No AT0 N OF MME⊙AGUA,ANDc°srAT RADIAL VELOCITY ( As sEEN IN THE RomTIwG

FURTHER BASICS 5-1 · LINEAR MOMENTUM m NEWTON'S LAW ∴F=P ow TAKE THE MOMENT OF MDMENTUM ANGULAR MOMENTUM MUST EXPLICITLY OEFINE

NEWTONs L丹WS ① BoDY CoNTINUES玉 N TTS STATE OF MOT(0N DR REST UNLESS FORCED DI RECTIoNs IMPoRTA. 儿L M5T3 E AN NIERT升L ACELERATION