A single-stage rocket is in deep space coasting at \(v_{\text {rocket }, \mathrm{i}}=2.0 \times 10^{3} \mathrm{~m} / \mathrm{s}\). It fires its engine, which has an exhaust speed of \(v_{\text {exhaust }}=1.0 \times 10^{3} \mathrm{~m} / \mathrm{s}\). What is the rocket's speed \(v_{\text {rocker,f }}\) after it has lost one-third of its inertia by exhausting burned fuel? Assume that the fuel is cjected all at once.