A 16 kg object is acted on by a conservative force given by F = (-2.9)x + (-4.8)x2, with F in newtons and x in meters. Take the potential energy associated with the force to be zero when the object is at x = 0. What is the potential energy of the system associated with the force when the object is at x = 2.0 m? I found this answer to be 18.6 J But I can't get the second half of the question... If the object has a velocity of 5.0 m/s in the negative direction of the x-axis when it is at x = 5.0 m, what is its speed when it passes through the origin? I thought I could do it using the formulas for constant acceleration but I don't know the acceleration or the time. Any suggestion for what formula to use?