Engines By: Daniel TUhy

What do you think of when you hear the word “engine”?

Fish bowl - Pre discussion knowledge Divide the whole class into two groups. Group #1 will arrange chairs in a circle in the middle of the room. Group #2 will stand around group #1, creating a “fish bowl”. Group #1 will discuss their current knowledge of engines. Talk about what you know about engines, nothing is off limits. Group #2 must remain quiet while group #1 is discussing! Group #2 will get a chance to discuss near the end of the presentation. After group #1 has shared their current knowledge, group #2 can share their current knowledge

What is an engine? Engine noun en·gine \ˈen-jən\ a machine that changes energy (such as heat from burning fuel) into mechanical motion

Types of engines An engine can be put into a category according to two criteria: the form of energy it accepts in order to create motion, and the type of motion it outputs. There are 4 main types of engines: Heat engines Non-thermal chemically powered motors Electric motors Physically powered motors

Heat engines a heat engine is a system that converts heat or thermal energy to mechanical energy, which can then be used to do mechanical work. Examples of heat engines: External combustion engine (steam engines) Internal combustion engine (gasoline engines)

External combustion engines An engine, such as a steam engine, in which the fuel is burned outside the engine cylinder. https://www.youtube.com/watch?v=IP1YxYKCt0U

Internal combustion engines An engine, such as an automotive gasoline piston engine or a diesel, in which fuel is burned within the engine proper rather than in an external furnace, as in a steam engine. https://www.youtube.com/watch?v=w-j8QvsiAdU

Non-combustion heat engines Some engines convert heat from non-combustive processes into mechanical work, for example a nuclear power plant uses the heat from the nuclear reaction to produce steam and drive a steam engine.

Environmental effects of heat engines The operation of heat engines typically has a negative impact upon air quality and ambient sound levels. The burning of fossil fuels to power most heat engines releases gases that may pollute the earths atmosphere. Pollution caused by heat engines has created interest in the discovery of alternative power sources. What are some examples of alternative power sources?

Non-thermal chemically powered motor Non-thermal motors usually are powered by a chemical reaction, but are not heat engines. Example: Molecular motor - motors found in living things The life processes that allow a living organism to transfer chemical energy into mechanical energy within the organism’s body

Electric Motors An electric motor uses electrical energy to produce mechanical energy, usually through the interaction of magnetic fields and current-carrying conductors. Electric motors have 5 main components: Rotor- turns the shaft Stator- stationary, contains magnets Air gap- gap between rotor and stator Windings- conductive coils wrapped around the core of the rotor Commutator- used to switch the input of most DC machines and certain AC machines

Activity #1 Turn to activity #1 in your handout and build a simple electric motor.

Physically powered motors Physically powered motors are powered by potential or kinetic energy. This energy can come from things such as falling rocks, falling water or moving air.

Activity #2 Turn to activity #2 in your handout and build a mousetrap car.

Activity #3 Turn to activity #3 in your handout and create a “Hovercraft”

Fish bowl- post discussion knowledge Set up the fish bowl just like you did at the beginning of the presentation Group #2 will now take the seats in the middle of the fish bowl and will be the only students discussing the knowledge they have gained from the presentation. After group #2 has shared their current knowledge, group #1 can shared their current knowledge