Friction

All friction opposes or goes against motion. Friction occurs when two things rub against eachother. Friction happens because although objects might look smooth if you look at them microscopically they are actually very rough and jagged. A situation where there is a heavy object is draged acoss a rough surface. A situation where there isn't a lot of friction is when there is a small object draged across a smooth surface. Friction relates to Newton's 1st Law of Motion because an object at rest wants to stay at rest and an object in motion wants to stay in motion unless acted upon by an outside force and friction is an outside force and that is y objects in motion stop or slow down.