Transcript What Is Energy Power Point

Chapter 13
Energy
What is Energy
Remember…Work = force x distance!
Energy = the ability to do work
So energy gives us the ability to cause a
force to move some object to do work
-energy is transferred from one
object to another
Power
Remember…Power = Work ÷ time
If work is just energy being
transferred, then power is the
measure of the amount of energy
being transferred within a set time.
Power = Energy transferred / time
Connections
• ENERGY IS WORK!
• No matter how you do the work
(with or without simple machines),
the amount of work done is the
same.
• No matter how you transfer energy
(with or without simple machines),
the amount of energy transferred
is the same.
Major Energy Types
• Kinetic Energy- (“moving energy”)
energy an object has because it is
moving
• Potential Energy- (“stored energy”)
energy an object possesses but has
not used yet
–The object is not moving yet, but it
could…it has the potential to move
Kinetic Energy (KE)
• KE = (mass)(velocity2)
2
•
*measured in Joules
-If mass increases, then KE increases
-if velocity increases, then KE
increases
Potential Energy (PE)
• There are many types of
PE…but the ones we will study
are Gravitational PE and
Elastic PE
Gravitational PE
• Gravitational PE = PE that depends on how
high off the ground the object is sitting
• Gravitational PE = Weight x Height *measured
in Joules
-If weight increases, the PE increases
-If height increases, the PE increases
KE and PE Can Act Together
• The girl in the air has both KE
and PE
• Her KE is the energy that it
took to throw her into the air
and the movement of her
falling
• Her PE is the energy that she
has once she is at the very top
of the throw, right before she
starts to fall. Here, she is not
in motion and has the potential
to fall. Her PE turns into KE
when she starts falling.
Elastic PE
• Elastic PE = PE created when objects are
stretched or compressed
– When you stretch a rubber band, it has the potential
to snap back to its original shape. When you flick
one across the room, you are transferring the
elastic PE from the stretch into KE when you
release it to make it fly.
– When you squeeze a stress ball, it has the potential
to decompress. Elastic PE is transferred into KE
when it returns to its original shape.
Formulas
• Work = Energy = force x distance
• Measured in Joules
• Power = Work / time = Energy transferred / time
• Measured in Watts
• KE = (mass)(velocity2)
2
• Measured in Joules
• Gravitational PE = Weight x Height
• Measured in Joules