For each topic describe in a brief paragraph 1) Its key characteristics and 2) A personal observation, or an experience with, or an example of a real world application of the topic.
A) frictional force
b) tension force
c) centripetal force
Friction force arises from motion of one object with respect to another when the two objects are within contact distance. This is due to the surface molecules of one object forming atomic bonds with the surface molecules of the other object. These bonds apply a force that resists any motion of the objects (which break the bonds). Friction force depends on the relative speed of the objects with respect to one another, being smaller at higher speeds. For all practical applications, the friction force is constant at rest (called static friction) and a different constant as the objects move (called kinetic friction). The friction force obviously depends also on the type of materials the objects are made of, the roughness of the surface etc. The friction force direction is always opposite the motion of the object it applies to.
Friction plays a major role whenever two parts rub each other. In most cases we want to reduce friction, since friction causes loss of energy through heat. In pistons engines we reduce the friction force between the smooth piston and the smooth cylinder by coating the parts with viscous fluid (oil) which has lower surface bonding force than metal (actually, very smooth metal objects have high friction between them - contrary to conventional wisdom). If oil is not applied to the ...
The 821 word solution clearly explains the concepts.