A constant force acts on a particle along a straight line. The force–displacement graph is: \(F=8\,\text{N}\) from \(x=0\) to \(x=3\,\text{m}\), then \(F=2\,\text{N}\) from \(x=3\) to \(x=7\,\text{m}\). If the particle starts from rest and has mass \(2.0\,\text{kg}\), what is its speed at \(x=7\,\text{m}\)?