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.

Definition of Energy…

The ability to do work.

Potential to due work: potential energy

or Putting energy into motion:

kinetic energy

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.

Standing stillRunning

Definition of Kinetic Energy…

The energy of motion/movement

Measured by:KE= ½ (Mass) (Velocity)

2

Use a balance to measure mass.

EX

AM

PLES

of E

NER

GY

PO

TEN

TIA

LK

INETIC

Stretching a rubber band

Water at the top of a waterfall

Yo–Yo held in your hand

Drawing a bow and arrow

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.

9

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.

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

KNOWLEDGE CHECK

1. 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!

KNOWLEDGE CHECK