A simple machine is a mechanical device that changes the direction or magnitude of a force. In general, they can be defined as the simplest mechanisms that use mechanical advantage (also called leverage) to multiply force. Usually the term refers to the six classical simple machines that were defined by Renaissance scientists: Lever Wheel and axle Pulley Inclined plane Wedge Screw A simple machine uses a single applied force to do work against a single work load. Ignoring friction losses, the work done on the load is equal to the work done by the applied force. The machine can increase the amount of the output force, at the cost of a proportional decrease in the distance moved by the load. The ratio of the output to the applied force is called the mechanical advantage. Simple machines can be regarded as the elementary "building blocks" of which all more complicated machines (sometimes called compound machines) are composed. For example, wheels, levers, and pulleys are all use

Keynesian economics (sometimes Keynesianism, named after the British economist John Maynard Keynes) are the various macroeconomic theories and models on how aggregate demand (total spending in the economy) strongly influences economic output and inflation. In the Keynesian view, aggregate demand does not necessarily equal the productive capacity of the economy. Instead, it is influenced by a host of factors (sometimes behaving erratically) affecting production, employment, and inflation. Keynesian economists generally argue that aggregate demand is volatile and unstable and that, consequently, a market economy often experiences inefficient macroeconomic outcomes - a recession, when demand is low, or inflation, when demand is high. Further, they argue that these economic fluctuations can be mitigated by economic policy responses coordinated between government and the central bank. In particular, fiscal policy actions (taken by the government) and monetary policy actions (taken by the ce

Criminal psychology is the study of the views, thoughts, intentions, actions and reactions of criminals or suspects. It is a subfield of criminology and applied psychology. Criminal psychologists have many roles within legal courts, including being called upon as expert witnesses and performing psychological assessments. Some types of psychiatry also deals with aspects of criminal behavior. Several definitions are used for criminal behavior, including behavior punishable by public law, behavior considered immoral, behavior violating social norms or traditions, or acts causing severe psychological harm. Criminal behavior is often considered antisocial in nature. Criminal psychology started in the late 18th century. There were four key aspects of the development of criminal psychology: philosophical, medical, legal and biological. Before criminal psychology, there was a conflict in criminal law between medical experts and court judges on determining how to proceed with a majority of case