A pulley is a type of simple machine that consists of a wheel with a groove to hold a rope or cable. It can be used to change the direction of force and, in certain systems, can provide mechanical advantage.
Lubricants, such as oil or grease, reduce friction by creating a thin layer between surfaces, allowing them to move more smoothly against each other. Increasing weight or roughening the surfaces would increase friction, and increasing temperature might increase the friction between surfaces.
Combustion is the chemical process in which fuel reacts with oxygen to produce heat, which is then converted into mechanical energy in the engine. This is the basic principle of how most internal combustion engines work.
Mechanical advantage is increased when the effort arm (the distance from the fulcrum to where the force is applied) is longer. A longer effort arm allows you to lift a heavier load with less effort.
A wrench is the proper tool for tightening or loosening bolts and nuts. Hammers are used for striking, screwdrivers for screws, and pliers for gripping objects.
