Download B11 Potential and Kinetic Energy Notes

Potential
and Kinetic
Energy
What is Energy?
• Energy – the ability to do work
–does NOT have mass or take up space
–Measured in the unit joules
• 2 categories of energy
–Potential Energy
–Kinetic Energy
Forms of Energy
• Energy can take different forms
Potential Energy
Kinetic Energy
Chemical
stored energy in bonds
Thermal
energy of moving particles (heat)
Elastic
stored energy due to tension
Mechanical
energy found in objects in motion
Nuclear
stored energy in the nucleus of an atom
Electrical
movement of electrons
Gravitational
stored energy due to position above
ground
Sound
longitudinal waves that are heard
EM Waves
all the waves in the EM spectrum move
Law of Conservation
of Energy
• Law of Conservation of Energy –
no new energy is created nor
destroyed, it’s just transferred
from one form to another
Potential Energy
• Potential Energy – stored energy of
position
–Has the “potential” to do something
Kinetic Energy
• Kinetic Energy – energy of motion
Energy Transformation
• When you lift the marble off
the ground it gets potential
energy because of its height
Energy Transformation
• As the marble moves down the
track, it loses potential energy, and
is converted into kinetic energy
Energy Transformation
• The marble slows down as it goes
uphill because kinetic energy is being
changed back into potential energy
Energy Transformation
Animated Roller Coaster
Energy Conversion
Energy Conversion
Energy Conversion
Energy Conversion
What kind of energy transformations
are occurring here?
Potential or Kinetic?
Moving car
Kinetic
Potential or Kinetic?
Tree branch
Potential
Potential or Kinetic?
Bent car fender
Potential
Potential or Kinetic?
Balloon filled with
water
Potential
Potential or Kinetic?
Log of wood
Potential
Potential or Kinetic?
Balloon squirting
around
Kinetic
Potential or Kinetic?
Person inside a
moving car
Kinetic
Potential or Kinetic?
Both
Potential or Kinetic?
Kinetic
Potential or Kinetic?
Kinetic
Potential or Kinetic?
An airplane circling in
preparation for landing
Kinetic
Potential or Kinetic?
A pile of coal that
will be used for fuel
Potential
Potential or Kinetic?
An unlit firecracker
Potential
Potential or Kinetic?
Glucose stored in plants as
a result of photosynthesis
Potential
Potential or Kinetic?
Burning log of
wood
Kinetic
Potential or Kinetic?
A dam holding back
a river’s water
Potential
Potential or Kinetic?
A marble rolling
down the aisle
Kinetic
Potential or Kinetic?
A new car battery
Potential
Potential or Kinetic?
An ant crawling
across a sandwich
Kinetic
Potential or Kinetic?
A tennis racket about to
crash down on a ball
Potential
Potential or Kinetic?
Energy at rest
Potential
Potential or Kinetic?
A mousetrap set
and ready to spring
Potential
PE= Joules (J)
Example
An 80kg man is jogging at a rate of 4m/s. He has
kinetic energy. Calculate it:
• KE = ½ x mass x velocity2
• KE = ½ x 80kg x (4m/s)2
• KE = ½ x 80 x 16
• KE = 40 x 16
• KE = 640 J
•
Example
• A 420kg boulder sits on top of a 100m cliff.
What is the potential energy?
• PE=mgh
• PE = (420kg)(9.8 m/s2)(100M)
• PE=411,600 J