1. ENERGY

2. Energy Is transferred within a SYSTEM of objects Isn’t a “thing”.
Analogy: Wealth

3. Eg -- Gravitational Potential Energy
energy due to an object’s change in height above earth (or other celestial body)
Evidence : Δ height above h = 0
h = 0 meters
System: an object and the earth (or other large object). Eg is impossible with one object alone.

4. Echem --Chemical Potential Energy
energy transferred in chemical reactions (transfer of electrons)
Evidence: food
batteries
fuel

5. Eel -- Elastic Potential Energy
energy stored in a spring or other elastic object
Evidence : object is de-formed (and it can re-form)

6. Ek -- Kinetic Energy
Evidence: velocity (motion)

7. Edis -- Dissipated Energy ----
Energy transferred to the surrounding environment.
Evidence: light, heat, sound; friction

8. Summary
How we know Eg Ek
Echem
Eel
Edis

9. Mass energy Converted by nuclear reactions
Other Energy we won’t be discussing right away
Mass energy
Converted by nuclear
reactions

10. Electric Energy Magnetic Energy
Other Energy we won’t be discussing right away (or at all)
Electric Energy
Stored in an electric field -- due to + and – charges separated from each other
Magnetic Energy
Stored in a magnetic field - due to North and South poles of a magnet separated from each other, (or from moving charges)

11. Q: How do we show Energy Transfers between objects?
Answer: Energy Bar Charts
Show Energy distribution at 2 or more instants in time

12. Examples of Bar Charts to show Conservation of Energy within a system
2010 olympics - aerial skiing (start at 00:43 sec)

14. Aerial skiing Eg Ek Edis Eg
Top
(before jump)
On ramp
In air
stopped Ek
Edis Eg Eg
Energy is always dissipated to other objects in the system as time goes on Eg Ek
Edis
Edis

15. worlds tallest bungee jump - start at 1:40

16. Bungee Jump Eg Ek Edis Eg Eg Ek Edis EEl Edis In air Top (before jump)
During stretch of elastic
stopped Eg Ek
Edis Eg Eg Ek
Edis
EEl
Edis

17. What is this story? Ek Ek Eg
Edis Eg
Edis

18. What is the physical meaning of each SLOPE and AREA?
Avg. Velocity
Acceleration
jerk
X (m)
v (m/s)
t(s)
a (m/s2)
t(s)
t(s)
meaningless
Displacement = Δx
Area: Δv
Gravitational Field Strength (N/kg)
Mass (N/m/s/s = kg)
meaningless μ
Slope:
a (m/s2)
ΣF (N)
Mass (kg)
Fg = weight (N)
t (S)
ΣF (N)
Ff (N)
FN (N)
meaningless
Impulse
meaningless
meaningless
Area: