A cart with initial total mass \(m_0\) moves along a horizontal, frictionless track at a constant speed \(v_0\). Sand leaks out through a hole in the bottom of the cart at a constant mass rate \(\alpha\), such that the mass of the cart and its remaining contents as a function of time is given by \(m(t) = m_0 - \alpha t\). Which of the following expressions represents the magnitude of the rate of change of linear momentum \(\left|\dfrac{dp}{dt}\right|\) of the cart and its remaining contents?