A vehicle of mass \(m\) is initially at rest at position \(x = 0\) on a horizontal, frictionless track. Starting at time \(t = 0\), the engine delivers a constant net power \(P_0\) to accelerate the vehicle along the positive \(x\)-axis. Which of the following expressions represents the position \(x(t)\) of the vehicle as a function of time \(t\)?