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Directions
• ISN pg. 33- Kinetic & Potential Energy, book
pgs.446-452
– Add to TOC
• You only have to copy down what is in purple
and the information on the 2 new formulas:
KE and PE
• When you complete the notes write your
summary and look at the last slide for the next
set of directions
Energy and Work
• Work- done when a force moves an object
through a distance, a transfer of energy
– Measured in joules (J)
• Energy- the ability to do work
– It is known by the changes it causes
– Examples are sound and motion
– Measured in joules (J)
• 1 joule = 1 newton-meter
• When work is done on an object, energy is
transferred to that object
Kinetic Energy
• Kinetic Energy- the energy of motion
– Comes from the Greek work kinetos, meaning
“moving”
– The kinetic energy of any moving object depends
upon its mass and speed.
Potential Energy
• Potential Energy- energy that is stored as a
result of position or shape
– Stored energy gets converted into kinetic energy
– You can store energy just by picking up a book and
holding it. Let go, and that stored energy will turn
into the kinetic energy of motion
Gravitational Potential Energy
• Gravitational Potential Energy- potential
energy that depends upon an object’s height
– The PE increases when an object is raised to a
higher level
– Depends on an object’s mass, height, and
acceleration due to gravity (9.8 m/s2)
Elastic Potential Energy
• Elastic Potential Energy- PE of an object that
is stretched or compressed
– Said to be elastic if it springs back to its original
shape after it is stretched or compressed
– Can also be stored in objects that are compressed,
such as springs
– Broken rubber band: it’s elastic PE is converted
into kinetic energy
NEXT (directions)
• On your interactive page 32, work out the “math
practice” problems from your book on page 448
(SHOW YOUR WORK). ALSO, include
pictures/chart/table/something demonstrating KE & PE
– There are 3 problems on kinetic energy
• When using the KE formula, ONLY velocity gets squared
• I have worked out problem #3 on the next slide. When solving for
velocity, some of you may have a more difficult time. Do the best
you can.
• If you look on page 449, you can see a worked PE energy problem
• HOMEWORK: KE & PE math practice worksheet. Do the
best you can. Show your work. Pay attention to the
worked problems in your book. Use the formulas at the
top of the page to help you. I will check for it.
Math Practice
• Problem #3:
Step 1: plug your numbers into
the correct spot in the formula
Step 2: simplify by multiplying
½ and 50. this equals 25
Step 3: divide both sides by 25.
this leaves you with 720 = v2.
YOU HAVE TO GET RID OF THE
SQUARE BY TAKING THE
SQUARE ROOT.
Step 4: the square root of 720
= 26.8 m/s