ch8_jbtk


 * Energy:**
 * Potential Energy** is the energy of position and potential energy vaires with the amount of **Kinetic Energy**.
 * Potential Energy is expressed as Mass x Gravity x height (MGH)

Gravitational Potential Energy = weight x height Mechanical Energy:** is using both **potential energy** and **kinetic energy** and decides the true energy that an object exerts. When work is described a as being "How long?" in a variation of distance the equation reads as Force x Distence (W=Fd) Basically work is the movement of something over time and distance. 2000N of force going a distance of 4 meters the equation is 2000(4)= 8000J Power is measured in Watts (W). So if there is 500J of work done over a 5 second time there is 100W of Power.
 * Gravitational Potential Energy:**
 * Kinetic Energy** is the energy of motion and is inversly proportional to **Potential Energy**.
 * Kinetic Energy is expressed as (1/2) mass x velocity squared ((1/2)mv^2)
 * If the speed of an object is doubled, the kinetic energy of the object is quadrupled.
 * it takes 4x as much work to double the kinetic energy.
 * Both Kinetic and Potential Energy are measured in Joules (J)
 * Work:** When work is described as "How long?" meaning a variation of time the equation reads as Force x Time (W=FT) This is called **Impulse**
 * Power:** Doing work does not describe a human because if a human is running he gets tired and therefore is not running at a constant pace, so we use Power to determine work and distance. Power is described as Force x distance/ Time Interval (Fd/T) or more simply Work done / Time Interval (W/T).

Energy cannot be created or destroyed. It can be transformed from one form to another, but the total amount of energy never changes.
 * Law of Conservation of Energy:**

Total work input theoretical mechanical advantage
 * Machine:** a device used to multiply forces or simply to change the direction of forces.
 * **Lever** - the work done at one end is equal to the work done on the load at the other end.
 * **Fulcrum** - pivot point of the lever
 * **Pulley** - a type of lever that can be used to change the direction of a force
 * Mechanical Advantage:** The ratio of output force to input force for a machine
 * Efficiency** = __Useful work output__ or __actual mechanical advantage__
 * efficiency will always be a fraction less than 1
 * example .45 x 100% or 45% efficiency
 * a 4 engine airplane gives out .25 efficiency so total it gives out 100% efficiency (25% per engine)
 * Energy for Life:** all life needs some sort or energy whether it be a human needing food and carbs for energy or plants needing sunlight (photosynthesis) so they can survive.