Transcript TOPIC: Energy AIM: What are the 5 forms of energy?

TOPIC: Energy
AIM: Describe potential and kinetic energy and
conversions that can occur between these two
forms of energy.
Do Now: Take out HW ditto
Top of the Ditto on the back of yesterday’s notes.
HW: Bottom of Physical and Chemical Properties
Review Ditto
Chemistry Castle Learning due on Tuesday!
Energy
• Ability to do work
• Unit = JOULES (J)
Law of
Conservation
of Energy
• Energy cannot be
created or
destroyed, only
changed from one
form to another
Think of energy as money. $100 can be saved in many
forms…
Cash in your wallet, a bank account, travelers’ checks, gold
or silver coins…
Money can be transferred to different forms.
It can be deposited in a bank account, or traded for gold.
No matter what form, money is money…
The same is true for energy. Energy from the sun and
energy from food are only different forms of the same
thing.
Kinetic
Energy
• Energy of motion
What can
cause an • Increase in velocity
increase (speed)
in KE?
• Larger mass
Potential • Stored energy
Energy
• Object is not moving
Examples 1. Stretched rubber
of PE
band = a lot of PE
– Let it go  PE is
released
2. Unlit match = PE stored till
lit
The massive ball of a demolition machine
and the stretched bow possess stored
energy of position = Potential Energy
The heavy ram of a pile driver and the
stretched bow possess stored energy of
position = POTENTIAL ENERGY.
Gravitational • PE that depends on
height
PE
• More height 
greater GPE
• Less height less
GPE
• Example: Person on a 3m diving
board has more GPE than
person on 1m board
• Change of energy from
Energy
1 form to another
Conversion
• KE  PE
• PE  KE
As the car loses height, it gains speed. PE
is changed into KE. The sum of the KE
and PE is constant. It never changes.
REVIEW:
KINETIC
OR
POTENTIAL
ENRGY?
The ram of a pile driver
has mechanical energy
When held up, it has
mechanical energy in the
form of potential energy.
As it falls, it has
mechanical energy in the
form of kinetic energy.
As it strikes the spike,
it applies a force to
move the spike (it does
work on it).
On the platform:
KE = 0J
PE = max
During the jump:
KE is increasing
PE is decreasing
PE  KE
In the water:
KE = 0J
PE = max
Let’s summarize…
1. What is energy. How is it measured?
2. Describe the Law of Conservation of Energy.
3. Explain the difference between kinetic energy
and potential energy.
4. What can cause an increase in kinetic energy?
5. Describe the relationship between height and
gravitational potential energy.
6. Describe the following energy conversions:
- jumping off a diving board
- throwing a ball into the air
A high diver steps off a diving platform that is
10m above the water. If no air resistance is
present, during the fall there will be a decrease in
the diver’s
1. gravitational potential energy
2. total mechanical energy
3. kinetic energy
4. momentum
Which of the following is an example of kinetic
energy?
1. A car not moving
2. Water falling off a dam
3. A rock resting on a ledge
4. A person sitting in a chair
Which of the following increases when a metal
spring is stretched horizontally?
1. Potential energy
2. Kinetic energy
3. Gravitational potential energy
4. Electrical energy
What happens to the kinetic energy and
gravitational potential energy of a ball during free
fall?
1. GPE and KE both increase.
2. GPE and KE both decrease.
3. GPE decreases and KE increases.
4. GPE increases and KE decreases.
• If both of these balls are
traveling down a bowling
lane at the SAME speed,
which one would
have more kinetic
energy? Support your
answer.
Which skier will
have a greater
potential
energy? Support
your answer.
At which two points on
the pendulum, is the
pendulum experiencing
the greatest potential
energy?