1. Chapter 9 Energy and Energy Resources
Section 1
What is Energy?

2. Energy and Work- Working together
What is energy?
Energy is the ability to do work
What is work?
Work occurs when a force causes an object to move in the direction of the force. (Work transfers energy)

3. Kinetic Energy is Energy of Motion
An object which has motion-whether it be vertical or horizontal motion- has kinetic energy (KE)
Three forms of KE are vibrational, rotational, and translational
To keep it simple, we will focus on translational KE or the energy due to motion from one location to another

4. Potential Energy Is Energy of Position
Potential energy is the energy an object has because of its position or shape.

5. Potential Energy Is Energy of Position
When in their resting position, they have no energy. The potential energy comes from the change in shape or position from it’s usual shape

6. Potential Energy Is Energy of Position
A rubber band is another good example of potential energy.
No energy
potential energy

7. Gravitational potential energy is the energy stored in an object as the result of its vertical position or height.
The gravitational potential energy of the massive ball of a demolition machine is dependent on two variables - the mass of the ball and the height to which it is raised.

8. There is a direct relation between gravitational potential energy and the mass of an object.
More massive objects have greater gravitational potential energy.
There is also a direct relation between gravitational potential energy and the height of an object.
The higher that an object is elevated, the greater the gravitational potential energy.

9. To determine the gravitational potential energy of an object, a zero height position must first be arbitrarily assigned. Typically, the ground is considered to be a position of zero height. In the lab, the desk could be zero height.
Since the gravitational potential energy of an object is directly proportional to its height above the zero position, a doubling of the height will result in a doubling of the gravitational potential energy. A tripling of the height will result in a tripling of the gravitational potential energy.

10. Forms of Energy: Thermal Energy
All energy involves either motion or position
Thermal energy: all particles of matter are in constant motion so they have kinetic energy. Particles also have energy because of molecular arrangement
Thermal energy is the total energy of the particles that make up an object

11. Forms of Energy: Chemical Energy
Chemical energy is the energy of a compound that changes as its atoms are rearranged to form new compounds
Chemical energy is a form of potential energy
When compounds, like sugar in some foods are formed, work is done to bond the atoms to form molecules

12. Forms of Energy: Electrical Energy
Electrical Energy is the energy of moving electrons
When an electric appliance is plugged in to an outlet, the electrons in the wires move back and forth transferring energy and producing the work of the stereo which is to produce sound.
Electrical energy can be a form of potential energy

13. Forms of Energy: Sound Energy
Sound is created by the movement of air past the vocal cords making them vibrate
Sound energy is caused by an objects vibrations
Sound energy is a form of potential and kinetic energy

14. Forms of Energy: Light Energy
Light energy is produced by the vibrations of electrically charged particles

15. Forms of Energy: Nuclear Energy
Nuclear energy is formed by fusing nuclei or splitting them…
fusion or fission

16. Energy and Machines
You transfer energy to the nutcracker and it transfers energy to the walnut
The nutcracker will not transfer more energy to the walnut than you transfer to the nutcracker

17. Energy and Machines Machines are energy converters
When machines transfer energy, energy conversions can often result

18. Let’s summarize What determines an objects thermal energy?
An objects thermal energy depends on its temperature, the arrangement of its particles, and the number of particles in the object

19. Let’s summarize
Describe why chemical energy is a form of potential energy.
When a substance forms, work is done to bond particles of matter together. The energy that creates the new bonds is stored in the substance as potential energy

20. Let’s summarize
When you hit a nail into a board using a hammer, the head of the nail gets warm. IN TERMS OF KINETIC AND POTENTIAL ENERGY, DESCRIBE WHY THIS HAPPENS.
The kinetic energy of the moving hammer is transferred to the head of the nail, causing particle sin the nail to move faster. The faster the particles move, the greater their thermal energy.

21. EQ #1 Explain the relationship between energy and work
Energy is the ability to do work. Work cannot occur without energy

22. Let’s Review
When you bounce a basketball, you give it kinetic energy. At the moment the ball hits the ground, its kinetic, its kinetic energy energy is greatest and its potential energy is zero. At that moment, the change in the shape that occurs when it hits the ground gives the ball potential energy that is used when the ball moves back upward. When the ball bounces back up toward your hand , its kinetic energy is converted into potential energy because the position changes. At the moment the ball is at the top of its bounce, its kinetic energy is zero.

23. Why energy conversions are important
They make energy useful by converting energy to a form of energy we can use
Energy efficiency is a comparison to the amount of energy before a conversion with the amount of useful energy after a conversion…efficiency means less waste
Work input is always greater than work output

24. Baseball hitting a bat