# Big Idea 11 : Energy Transfer and Transformations

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Big Idea 11 : Energy Transfer and Transformations
A. Waves involve a transfer of energy without a transfer of matter. B. Water and sound waves transfer energy through a material. C. Light waves can travel through a vacuum and through matter. D. The law of Conservation of energy: energy is conserved as it transfers from one object to another and from one form to another.

Benchmark Description & Number:
SC.6.P.11.1   Explore the law of conservation of energy by differentiating between potential and kinetic energy. Identify situations where kinetic energy is transformed into potential energy and vice versa.

Putting energy into motion:
Definition of Energy… The ability to do work. Potential to due work: potential energy or Putting energy into motion: kinetic energy

PE= (weight) (gravity) (height)
Potential Energy… Energy due to an object’s position or stored energy (the ability to move). Measure by: PE= (weight) (gravity) (height) (the earth’s gravitational pull 9.8 m/sec sq)

Potential Energy Converted to Kinetic Energy…
When energy that is stored is put to use, an object begins to move. The energy is now transferring from potential energy into kinetic energy. Running Standing still

Definition of Kinetic Energy…
The energy of motion/movement Measured by: KE= ½ (Mass) (Velocity) 2 Use a balance to measure mass.

EXAMPLES of ENERGY POTENTIAL KINETIC Stretching a rubber band
Water at the top of a waterfall Yo–Yo held in your hand Drawing a bow and arrow KINETIC Shooting a rubber band Water falling over the fall A Yo-Yo in motion Releasing the arrow from the bow

Energy Transformations
Energy conservation and conversion are important considerations for all systems. Mechanical systems have both potential energy and kinetic energy. When work is done, energy changes from one form to another. ex. As a roller coaster ascends to its highest point, PE is at its highest. (needs to store energy in order to get down). As the coaster descends down, the PE is transferred into KE (greater speed). Energy is neither created nor destroyed during any process, only changed in form. 8/23/04

Conservation of Energy
Energy cannot be created or destroyed. If the total amount of energy in a system changes, it can only be due to the fact that energy has changed forms.

KNOWLEDGE CHECK If a tennis ball and basketball are dropped from one meter high, explain why both balls would not rebound the one meter?

KNOWLEDGE CHECK If a tennis ball and basketball are dropped from one meter high, explain why both balls would not rebound the one meter? Both balls would not rebound back to the starting point because of energy transformations. Holding the ball at 1 meter = PE while dropping the ball converts the PE into KE. Once the ball hits the floor, energy is transferred in the form of heat (friction between ball and ground). Friction such as air resistance is also causes a loss off energy from the ball. Therefore, the ball after hitting the ground does not have the same amount of energy as when released and cannot return to the same height. Try it!