Energy

  People do work (running, walking, etc.) because they have energy. So, energy is defined as the ability to do work. The important thing about energy is that it is conserved, cannot be created or destroyed.

   For example, if object 1 hits object 2, the energy from object 1 goes to object 2 and the molecules in object 2 can cause the energy to vibrate, or go around the room, etc. The energy doesn't disappear.

Energy can come in different forms.

                         Chemical: Energy contained within food, your body, and fuel. The examples are gasoline filled up in a car, and batteries.

 Thermal: Vibration and movement of the atoms and molecules within substances. Some
examples are water boiled in a kettle and rubbing your hands until it feels warm.

                                 Sound: Energy created from the vibration of air particles around a sound source. Some examples are clapping your hands and a plane taking off.

 Light: Energy created by the radiation of electromagnetic waves. Examples are a
fire and the sun shining.

                                   Electrical: Energy created from the presence and flow of electric charge. Lightning is an example of electrical energy in nature and also stroking a cat with long fur.

 Nuclear: Energy released from the reaction of the radioactive matters. The examples 

are atomic and hydrogen bombs and also the sun (the energy is transmitted from sun

to earth in the form of electromagnetic radiation).

Mechanical: Energy associated with motion.

 1.  Potential energy, the energy stored within an object.

Spring potential energy - an archer's bow and a sling shot is two examples because 

when someone pulls it, energy is stored within it until it is released.

Gravitational potential energy - an apple hanging on a tree and a swing
are two examples. Both examples have gravitational potential energy because of the position.
The potential energy within the objects relates to its distance above ground.

2.  Kinetic energy, the energy possessed by an object because of it's motion/movement.

An object falling off of a table and a water falling from a tap water are some examples.

ball rolling down a slope
- kinetic and potential energy-

An apple hanging from a tree
-potential energy-

Resources:




- http://plainenglish.viewshare.net/physics/mechanics/energy.shtml
- http://www.nmsea.org/Curriculum/Primer/forms_of_energy.htm
- http://www.eia.gov/kids/energy.cfm?page=about_forms_of_energy-basics
- www.wisegeek.com/what-is-electrical-energy.htm

What is work?

Work involves force and displacement of objects. It can also be defined as a transfer of energy. So to do work, there are some requirements:
- a force must cause displacement
- a force must have the same direction as displacement

The formula of work is force times distance because work is the application of a force over a distance.
(Force: W x D)
The unit of measurement for force is N (Newtons), distance is m (meters), and work is J (Joules).

Examples of work:
1. A woman is pushing a trolley. She transfers force to the bed until it moves, so it is considered as work.
2. Two men are lifting a box from the floor, they are producing force so the box is lifted.

Sources:
 http://www.edinformatics.com/math_science/work_energy_power.htm