An earthquake \(45 \mathrm{~km}\) from a city produces \(\mathrm{P}\) and \(\mathrm{S}\) waves that travel outward at 5000 and \(3000 \mathrm{~m} / \mathrm{s}\), respectively. Once city residents feel the shaking of the \(\mathrm{P}\) wave, how much time do they have before the \(\mathrm{S}\) wave arrives?