Transcript Total Energy

Law of Conservation of Energy
Energy cannot be created nor destroyed
Law of Conservation of Energy
• Total energy before = total energy after
• KEi + PEi = KEf + PEf
Example #1
5 kg
8m
Potential Energy
(gravitational)
PE = m g h
5 kg
PE = 392 J
PE = 294 J
Find the PE at
each red dot
8m
PE = 196 J
PE = 98 J
PE = 0 J
5 kg
Total Energy (PE+KE)
PE = 392 J
KE = 0 J
392 J
PE = 294 J
KE = 98 J
392 J
PE = 196 J
KE = 196 J
392 J
PE = 98 J
KE = 294 J
392 J
PE = 0 J
KE = 392 J
392 J
8m
PE = 392 J
KE = 0 J
Example
#2
5 kg
What is the velocity of the rock at
the bottom of the hill?
V = 2KE
m
V = 2(392 J)
5 kg
v = 12.5 m/s
PE = 0 J
KE = 392 J
8m
Energy Song
Picture this a penny,
Atop a hill and ready,
It’s not moving it’s steady,
Potential Energy.
(Chorus)
And now the penny’s rolling
Kinetic it’s a growing
Potential it’s now lowering
Conserving Energy
(Chorus)
Falling, falling faster
It is not hard to master
The idea of this transfer to
Kinetic Energy
(Chorus)
Reflect
• Write a statement that will help you to
remember the relationship between
Potential energy and Kinetic energy.
Rube Goldberg Energy Transfer
• http://www.youtube.com/watch?v=_ve4M4
UsJQo
• http://www.youtube.com/watch?v=qybUFn
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