Answer :

1. Frictional force

A naturally occurring force related to two bodies in motion is frictional force. Friction is a type of force which includes two bodies resisting each other –either motion of solid surfaces, fluid layers, material elements and compounds gliding against each other. They key point of this frictional force is that the two forces are in the opposite point of direction with each other. For example, when you are cold, as you rub your hands together notice that when your right hand is going upward, your left hand is downward and thus creates heat. That is one type of friction force outcome, the heat.