Problem
At first glance, it may appear that Hume violates commonsense when we can see for ourselves that most often when the ball is struck in a certain way, it really does end up in one of the pockets. Hume would have seen that too. So it must be that he is not really discussing the physical experience of playing billiards. What he is discussing is the mental process of our judging the movement of the ball. There is no physical law of cause to effect observable by our senses. The process of cause to effect is a mental construct or addition to our consideration of what happens to the ball. In other words, there is a gap missing between the ball and the fact that it ends up in the pocket.
Your problem is to use the information from our reading, to give a detailed explanation of what Hume says is wrong with the principle of causality. Explain what he means by the association of habit.