You are standing at x 0 m, listening to a sound that is emitted at frequency fo. At t = 0 s. the sound source is at x = 20 m and moving toward you at a steady 10 m/s. Draw a graph showing the frequeney you hear from t = 0 s. to t = 4 s. Only the shape of the graph is important, not the numerical values of f. fo- t (8) 1