2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/72545In this paper we prove global existence for certain multispeed Dirichlet-wave equations with quadratic nonlinearities outside of obstacles. We assume the natural null condition for systems of quasilinear wave equations with multiple speeds. The null condition only puts restrictions on the self-interactions of each wave family. We use the method of commuting vector fields and weighted space-time $L^2$ estimates.30 pages. To appear in Forum MathAnalysis of PDEs35L70; 42B99text