Without friction, energy transfer would be easier and stopping motion would be more difficult. If there was no friction, there would be no force slowing down motion when two objects rubbed against one another. A moving ball would stop if it hit a boulder, but without friction it would roll forever along a flat street. No matter how hard a driver jammed on the brakes, his car would not come to a stop, because brake pads rely on friction. Even the simple act of walking down the street would become dangerous. Without friction between the shoe and the street surface, walking would be much like trying to walk on an icy sidewalk. Trying to light a fire with a match would be ineffective, as striking a match relies on friction between the match head and the strike plate or another hard surface. On the other hand, energy transfer would be more efficient. A person shoving his friend into another person would find that shove to be more powerful, because the person being shoved would not have friction with the ground to slow him down. With friction, lubricants must be used to increase the efficiency of the moving parts of machinery and decrease the heat caused by the parts rubbing together.