Basic knowledge - engine
An engine or motor is a machine designed to convert one form of energy into mechanical energy.12 Heat engines, including internal combustion engines and external combustion engines (such as steam engines), burn a fuel to create heat, which then creates a force. Electric motors convert electrical energy into mechanical motion; pneumatic motors use compressed air and others?such as clockwork motors in wind-up toys?use elastic energy. In biological systems, molecular motors, like myosins in muscles, use chemical energy to create forces and eventually motion.
Public costs - car issue
The external costs of automobiles, as similarly other economic externalities, are the measurable costs for other parties except the car proprietor, such costs not being taken into account when the proprietor opts to drive their car. According to the Harvard University,11 the main externalities of driving are local and global pollution, oil dependence, traffic congestion and traffic accidents; while according to a meta-study conducted by the Delft University12 these externalities are congestion and scarcity costs, accident costs, air pollution costs, noise costs, climate change costs, costs for nature and landscape, costs for water pollution, costs for soil pollution and costs of energy dependency. The existence of the car allows on-demand travel, given, that the necessary infrastructure is in place. This infrastructure represents a monetary cost, but also cost in terms of common assets that are difficult to represent monetarily, such as land use and air pollution.
Why is the use of public transport is important especially in big cities?
In particular, many major urban centers there is more and more a problem with the huge traffic jams, especially during rush hours, which is why the authorities of many cities persuade motorists to give up to move your own vehicle and elected public means of transport. Although using public transport for sure we are exposed to the crowd on trams or buses, it should be induced to such exchange. True, motoring fans argue that the use of own car is much more comfortable, but we must bear in mind also that choosing the bus instead of the car contribute to fewer exhaust emissions.