1. What is energy?

2.  Energy- the ability to do work  When one object does work on another object, energy is transferred from the first object to the second object.  The unit for energy is Joule (J)– just like work.

3.  Kinetic Energy- energy in motion  All moving objects have kinetic energy  Kinetic Energy = KE = mv 2 2 ▪ M = mass (Kg)v = m/s ▪ Velocity has a greater effect on kinetic energy than mass does (because it’s squared)

4.  What is the kinetic energy of a car that has a mass of 1,200 Kg and is moving at a speed of 20 m/s?  What is the kinetic energy of a car that has a mass of 2,400 kg and is moving at 20 m/s? How does this kinetic energy of the car in the above example compare?

5.  What is the kinetic energy of a 4,000 Kg elephant that is running at 2 m/s? At 4m/s?

6.  Potential Energy- The energy that an object has because of the position, shape, or condition of the object  Gravitational Potential Energy - When you lift an object, you do work on it. When you do this, you transfer energy to the object and give the object gravitational potential energy.  energy stored as a result of position or height. ▪ GPE = weight x height ▪ GPE = Joules (J) Weight = Newtons (N) height = meters (m)

7.  What is the gravitational potential energy of a book with a weight of 13 N at a height of 1.5 m off the ground?  What is the gravitational potential energy of a cat that weighs 40 N standing on a table that is 0.8 m above the ground?

8.  What is the gravitational potential energy of a diver that weights 500 N standing on a platform that is 10 m above the ground?

9.  Mechanical Energy- the total energy of motion and position of an object.  Both kinetic and potential energy are kinds of mechanical energy  Mechanical Energy (ME) = potential energy + kinetic energy (J)(J) (J)

10.  What is the mechanical energy of a book being held in the air that has 100 J or potential energy and 50 J of kinetic energy?  What is the mechanical energy of a goose standing on a rock that has 75 J of potential energy and 60 J of kinetic energy?

11.  Thermal Energy- is all of the kinetic energy due to random motion of the particles that make up an object.

12.  Chemical Energy-The energy in a compound that changes as its atoms are rearranged

13.  Electrical Energy- is the energy of moving electrons.  (negatively charged particles in atoms)  Sound Energy- is caused by an object’s vibrations.  Light Energy- Produced by the vibrations of electrically charged particles.  Nuclear Energy- The energy that comes from the nucleus of an atom.  Fission and fusion

14.  Friction-A force that opposes motion between two surfaces that are touching

15.  Closed System- a group of objects that transfer energy only to each other.  Energy is conserved, not destroyed.

16.  Energy cannot be created or destroyed.  The total amount of energy in a closed system is always the same.  Some energy is always lost to thermal energy (heat). It’s not lost energy.

17.  A machine that will run forever without any additional energy  The machine will put out exactly as much energy as it takes in.  This is impossible because waste thermal energy always occurs due to friction.

18.  Energy Efficiency - is a comparison of the amount of energy before a conversion with the amount of useful energy after a conversion  More efficient = less friction/less lost energy