sentences: rolling on a surface is a kind of moving on a surface & the rubber ball is rolling across a surface ->  the rubber ball is moving on a surface  the rubber ball is moving on a surface & a rubber ball is a kind of object & friction occurs when two object 's surfaces move against each other ->  friction will occur between the rubber ball and the surface  friction will occur between the rubber ball and the surface & a rubber ball is a kind of object & friction causes the speed of an object to decrease ->  friction will cause the speed of the rubber ball to decrease  friction will cause the speed of the rubber ball to decrease & a rubber ball is a kind of object & the object will stop when its speed is decreased to zero -> friction will cause the rubber ball to stop by decreasing the speed of the rubber ball to zero