How fast should the platform move, vp, for the person to detect a beat frequency of 7.00 hz? take the speed of sound to be 344 m/s. express your answer numerically in meters per second using three significant figures. hints?

Delta (f) = f0 * v_rel/c, where v_rel is the relative velocity between source and observer. The source is moving at a speed v but the sound bounced off the wall and the receiver is moving toward it too. So, Delta (f) = f0 (2 V) / c Hence V = c Delta (f) / (2 f0) = 344 m/s * (7.00Hz / (2*245Hz)) = 4.91 m/s