In Extended Classical Mechanics (ECM), mass is not a fixed or intrinsic property of an object but emerges dynamically through gravitational interactions. This perspective challenges conventional notions of mass by proposing that it is induced or modified based on the surrounding gravitational field and energy conditions. ECM explains how effective mass can shift between positive, zero, or even negative values, offering deeper insights into mass acquisition, gravitational collapse, and antigravitational motion at cosmic and quantum scales.