関連ワード:  give me example of frictional force    give me one example of frictional force    give me some example of frictional force    give me two example of frictional force    give one example of frictional force    give five examples of frictional force    give three examples of frictional force    give some example of frictional force in day to day life    give me an example of drag force    give 2 examples of frictional force