6) I can't read graph A, but I will assume it is similar to graph B. The graph represents the position of an object with respect to time. The slope of this graph represents the velocity of the object. Since the graph is a straight line, the slope of the graph is constant and also the velocity of the object is constant. If the velocity is not changing the force on the object must be zero.
7) I can't see the data table but I will assume it is similar to example (6). In that case, the slope of the graph would represent the speed of the sound.
