1. Warm-Up *Turn in Potential Energy Practice
When a 2kg mass is attached to a vertical spring, the spring is stretched 10cm such that the mass is 50 cm above the table.
What is the gravitational potential energy associated with this mass relative to the table?
What is the spring’s elastic potential energy if the spring constant if N/m.
What is the total potential energy of this system?

2. Conservation of Energy

3. Conserved Quantities
As we have already learned, mass is a conserved quantity (Law of Conservation of Mass)
Mass of Light Bulb = Mass of all shattered pieces

4. Mechanical Energy
Mechanical Energy- the sum of kinetic energy and all forms of potential energy (gravitational & elastic).
Nonmechanical Energy- all other forms of energy (nuclear, chemical, internal, and electrical, thermal, radiant, acoustic)
Negligible or irrelevant for most problems
Motion of a Clock Pendulum
Highest point of swing- only gravitational PE
Other points of swing- KE
Elastic PE from springs inside

5. Conservation of Mechanical Energy
In the absence of friction and regardless of the path the object travels, the total mechanical energy remains the same.
Initial Mechanical Energy= Final Mechanical Energy
Kinetic Energy  Gravitational Potential Energy

6. Friction
Mechanical Energy is not conserved in the presence of friction.
When there is kinetic friction, kinetic energy is converted into a nonmechanical form of energy
Nonmechanical energy is no longer negligible.
Total Energy is ALWAYS conserved, but Mechanical Energy can be “lost”

7. Practice
Starting from rest, a child zooms down a frictionless slide from an initial height of 3.00 m. What is her speed at the bottom of the slide? Assume she has a mass of kg.

8. Warm-Up Create a concept map for energy. Include the following terms:
Radiant
Thermal
Nuclear
Gravitational
Kinetic
Acoustic
Mechanical
Potential
Internal
Electrical
Nonmechanical
Elastic
chemical.

9. Warm-Up
A person stands on a diving board 20 m above the water below. Draw a picture of this. Label the following on your picture:
The type of energy they have at the top
The type of energy when they have 10m above the water.
The type of energy the have right as they hit the water.
What do these all have in common?