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## PowerPoint Slideshow about 'Energy' - ostinmannual

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### Energy

Chapter 9 Section 4

Energy

Energy is the ability to do work or cause change

What is Transfer of Energy?

When an object or living thing does work on another object, some of its energy is transferred to that second object.

When energy is transferred, the object upon which work is done gains energy.

The SI Unit for both Work & Energy = Joule

A moving object, such as wind, can do work when it strikes another object and moves it some distance.When a breeze does work lifting leaves, it transfers energy to them.

Kinetic Energy

What is Kinetic Energy?

Energy an object has due to its motion

Depends on the objects MASS and its SPEED

Kinetic energy increases as mass increases or if its speed increases.

Kinetic Energy = ½ Mass x Speed2

BRAIN BREAK!

With your partner, create an analogy for Kinetic Energy and how mass and speed are related.

Potential Energy

- Stored energy that results from the position or shape of an object.
- Object has the potential to do work.

1) Gravitational Potential Energy

Related to an object’s height.

GPE = Weight x Height

Does a skier have more gravitational potential energy on a 50 meter high jump or a 40 meter high jump?

What is the GPE of a skier that weighs 500 Newtons and is on a 40 meter high ski jump?

2) Elastic Potential Energy

When an object gains Potential energy because it is stretched or squeezed.

What are some examples?

Archer pulling back on an arrow changes the shape of the bow…the bow now has more potential energy that can be used to send the arrow flying

Mechanical Energy

An object’s combined kinetic energy and potential energy

Mechanical Energy =

Kinetic Energy + Potential Energy

For example:

A football weighs 4 Newtons and has a mass of .4 kg

What is the football’s Kinetic Energy if it is moving at a speed of 14 m/s?

Kinetic Energy = ½ Mass x Speed2

39 Joules

What is the football’s Potential Energy if it is 3 meters above the ground?

Potential Energy = Weight x Height

12 Joules

What is the football’s mechanical energy?

Transformation between Potential & Kinetic Energy

- An object that rises or falls experiences a change in its kinetic and gravitational potential energy.

Active Art Textbook Link:

http://www.phschool.com/atschool/phsciexp/energy_transformations/index.html

The Kinetic Energy of the ball thrown into the air becomes gravitational potential energy. Its potential energy becomes kinetic energy as it falls.

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