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CP Sci 9- 1st Sem.

Gen Chem - 1st Sem.

Energy:

Objectives:

    1.    Name the three basic forms of energy.

    2.    State the law of conservation of energy.

Key Terms:

    energy    kinetic energy    potential energy    joule    law of conservation of energy

Web Resources:

 

Notes:

Energy is the term used to describe the capacity to produce heat or to do work.  There are two major forms of energy, Kinetic and Potential.  

Kinetic Energy (KE) is the energy of motion.  When an object is in motion, it carries kinetic energy in the amount of 1/2 multiplied by the mass multiplied by the velocity squared.  (1/2mv2)  Kinetic energy can also come in the form of mechanical energy (energy created by the gears of a machine) and thermal energy (heat created by the internal motion of particles of matter).

Potential Energy (PE) is the energy of position.  A coiled spring is an example of mechanical PE, water stored in a water tower is an example of gravitational PE, and chemicals stored in batteries are all examples of electrical and chemical PE.  

The Law of Conservation of Energy states that "...energy can neither be created nor destroyed, only changed from one form to another." 

What this means is that energy is constantly changing from one form to another.  PE from the water in the water tower changes to KE as it flows out.  It may be used to turn a large wheel which changes it to mechanical energy.  The large wheel may run a generator where the mechanical energy is being turned into electrical PE and heat.  As you can see the energy is not lost, simply changed.

Measuring Energy:

    The calorie (cal) is a common unit of measure and is the amount required to raise 1g of water 1oC.  It is also the name given to measure of energy in food (C). (C = 1000cal= 1kcal)  The unit for energy is the Joule named after the physicist James Prescott Joule.  The conversion for the two common measurements is 1cal = 4.184J

    Example:  An average candy bar contains 200 Calories.

        200C x 1000cal x 4.184J = 8.36 x 105J

            1                C          cal

 

 

 

 

 

 

 

 

 

Last modified: September 05, 2004