1. Science, Matter, Energy, and Systems2
Science, Matter, Energy, and Systems
Photo © Borut Trdina/iStockphoto

2. Energy Energy is all around you! You can hear energy as sound.
You can see energy as light.
And you can feel it as wind.

3. You use energy when you:
hit a softball.
lift your book bag.
compress a spring.

4. Living organisms need energy for growth and movement.

5. Energy Energy can be defined as the ability to do work.
If an object or organism does work (exerts a force over a distance to move an object) the object or organism uses energy.

6. Nature of Energy
Because of the direct connection between energy and work, energy is measured in the same unit as work: joules (J).
In addition to using energy to do work, objects gain energy because work is being done on them.

7. All forms of energy can be in either of two states: Potential Kinetic
States of Energy
All forms of energy can be in either of two states:
Potential
Kinetic

8. Energy Kinetic Energy Potential Energy
Stored energy and the energy of position
Kinetic Energy
Motion of waves, electrons, atoms, molecules, and substances
Review how the forms of energy are classified. Use the Forms of Energy handout to begin this discussion.

9. Chemical Energy Nuclear Energy Potential Energy Elastic Energy
Energy stored in the bonds of atoms and molecules
Nuclear Energy
Energy stored in the nucleus of an atom – the energy that holds the nucleus together
Potential Energy
Stored energy and the energy of position
Gravitational Energy
Energy of place or position
Elastic Energy
Energy stored in objects by the application of force.

10. Kinetic Energy Radiant Energy Thermal Energy Sound Energy
Electromagnetic energy that travels in transverse waves
Thermal Energy
Internal energy in substances – vibration or movement of atoms and molecules in substances a.k.a. “heat”
Kinetic Energy
Motion of waves, electrons, atoms, molecules, and substances
Sound Energy
Movement of energy through substances in longitudinal waves
Electrical Energy
Movement of electrons
Motion
Movement of substance from one place to another

11. Kinetic Energy Kinetic Energy is the Energy of Motion.
The faster an object moves, the more kinetic energy it has.
The greater the mass of a moving object, the more kinetic energy it has.
Kinetic energy depends on both mass and velocity.

12. K.E. = ½ mass x velocity2 Kinetic Energy
What has a greater affect of kinetic energy, mass or velocity? Why?

13. Potential Energy Potential Energy is stored energy.
Stored chemically in fuel, the nucleus of atom, and in foods.
Or stored because of the work done on it:
Stretching a rubber band.
Winding a watch.
Pulling back on a bow’s arrow.
Lifting a brick high in the air.

14. Gravitational Potential Energy
Potential energy that is dependent on height is called gravitational potential energy.

15. Gravitational Potential Energy
A waterfall, a suspension bridge, and a falling snowflake all have gravitational potential energy.

16. Gravitational Potential Energy
If you stand on a 3- meter diving board, you have 3 times the G.P.E, than you had on a 1-meter diving board.

17. Gravitational Potential Energy
“The bigger they are the harder they fall” is not just a saying. It’s true. Objects with more mass have greater G.P.E.
The formula to find G.P.E. is
G.P.E. = Weight X Height.
**weight = mass x acceleration due to gravity
w = mg

18. Energy Conversion
Energy can be changed from one form to another. Changes in the form of energy are called energy conversions.

19. All forms of energy can be converted into other forms.
Energy conversions
All forms of energy can be converted into other forms.
The sun’s energy through solar cells can be converted directly into electricity.
Green plants convert the sun’s energy (electromagnetic) into starches and sugars (chemical energy).

20. Other energy conversions
In an electric motor, electromagnetic energy is converted to mechanical energy.
In a battery, chemical energy is converted into electromagnetic energy.
The mechanical energy of a waterfall is converted to electrical energy in a generator.

21. Kinetic-Potential Energy Conversion
Roller coasters work because of the energy that is built into the system. Initially, the cars are pulled mechanically up the tallest hill, giving them a great deal of potential energy. From that point, the conversion between potential and kinetic energy powers the cars throughout the entire ride.

22. The Law of Conservation of Energy
Energy can be neither created nor destroyed by ordinary means.
It can only be converted from one form to another.
If energy seems to disappear, then scientists look for it – leading to many important discoveries.

23. Law of Conservation of Energy
In 1905, Albert Einstein said that mass and energy can be converted into each other.
He showed that if matter is destroyed, energy is created, and if energy is destroyed mass is created.
E = MC2

24. Energy Quality
High-quality, or concentrated energy, has a high capacity to do useful work.
Examples: high-temperature thermal energy, concentrated sunlight, high-speed wind, energy released from burning fuels)
Low-quality, or dispersed energy, has little capacity to do useful work.

25. Energy Changes Are Governed By Two Scientific Laws
First law of thermodynamics (law of conservation of energy)
Whenever energy is converted from one form to another in a physical or chemical change, no energy is created or destroyed.
Second law of thermodynamics
When energy is changed from one form to another, it always results in less high-quality energy.

26. 2.4 What Are Systems?
A system is a set of components that function/interact in some regular way.
Inputs
Throughputs
Outputs
Form of matter, energy, information
Examples: cell, human body, river, forest, dam, economy

27. System Model
Inputs, Throughputs, Outputs: This greatly simplified model shows the flow of matter, energy, and information into and out of a system.

28. Systems Respond to Change Through Feedback Loops
Feedback is matter, energy, or information that is fed back into a system as input and can affect system behavior.
Feedback loops
Positive feedback loops cause systems to change further in same direction.
Ecological tipping point: natural system locked into positive feedback loop
Negative feedback loops cause systems to change in opposite direction.