sentences: ground is a kind of object & a soccer ball is a kind of object ->  a soccer ball and ground are kinds of objects  a soccer ball and ground are kinds of objects & when the soccer ball is rolling, it is moving against the ground & friction occurs when two object 's surfaces move against each other ->  friction will occur between the rolling soccer ball and the ground  friction will occur between the rolling soccer ball and the ground & a soccer ball is a kind of object & friction causes the speed of an object to decrease -> friction will cause the speed of the rolling soccer ball to decrease