Meriam, Kraige & Bolton — Statics of Particles: Problem 2_57

⚡ Mecademy AIENG정역학 · ch2  Problem Statement 2/57 As part of a test, the two aircraft engines are revved up and the propeller pitches are adjusted so as to result in the fore and aft thrusts shown. What force F must be exerted by the ground on each of the main braked wheels at A and B to counteract the turning effect of the two propeller thrusts? Neglect any effects of the nose wheel C, which is turned 90° and unbraked. Problem 2/57 (a) Determination of the ground force F on main wheels ● Calculation Process 1. Present Final Formula: The two engine thrusts of magnitude act in opposite directions with a perpendicular distance between them. This pair of forces constitutes a couple. To maintain equilibrium, the ground must exert a counteracting couple of equal magnitude but opposite direction using forces on the main wheels A and B, which are separated by a distance . The moment equilibrium equation for couples is: 2. Substitute Values: Substitute the known values from the problem description and diagram: 3. Partial Operations: First, calculate the magnitude of the turning moment (couple) generated by the engines: From the diagram (top view), the top engine thrust is directed aft and the bottom engine thrust is directed fore, creating a counter-clockwise (CCW) moment of . 4. Final Calculation: Solve the equilibrium equation for the ground force magnitude : T=500 lb d = e 14 ft F d = w 8 ft M = engines M ground T⋅d = e F⋅d w (500 lb)⋅(14 ft)=F⋅(8 ft) M = engines 500×14=7000 lb⋅f