sentences: a stick is a kind of object & two sticks are rubbing against each other & if two objects are rubbing each other, then they are moving against each other ->  two sticks are moving against each other  two sticks are moving against each other & a stick is a kind of object & friction occurs when two object 's surfaces move against each other ->  friction will occur between two sticks  friction will occur between two sticks & friction causes the temperature of an object to increase & a stick is a kind of object ->  friction between two sticks will cause two sticks to increase in temperature  friction between two sticks will cause two sticks to increase in temperature & friction is a kind of force -> frictional force between two sticks causes them to increase in temperature