Please explain how to interpret this graph as well as the rest of the problem. Thank you!
Two horizontal forces 1 and 2 act on a 3.0 kg disk that slides over frictionless ice, on which an xy coordinate system is laid out. Force 1 is in the positive direction of the x axis and has a magnitude of 6.7 N. Force 2 has a magnitude of 9.0 N. Figure 5-34 gives the x component vx of the velocity of the disk as a function of time t during the sliding. What is the angle between the constant directions of forces 1 and 2?