Download P6 supp- energy conversion – 13 july 11

Energy
Conversion
P6 Science
Supplementary
13 July 11
A. Getting basic terms right
B. Clarify misconceptions
C. Explore examples of
energy conversion
1. Forms of Energy vs Sources of Energy
FORMS
SOURCES
(for producing electricity)
1. Light
2. Heat
3. Sound
4. Electrical
5. Kinetic (moving objects)
6. Potential
Eg.Gravitational potential
Chemical potential
Elastic potential
Wind
Running water
Solar (Sun)
Geothermal
Tidal
Nuclear
Fossil fuels
Electricity
(secondary source)
1 (a) Besides being
a form of energy,
electricity
(electrical
energy) is a also
a source of
energy. But it is a
secondary
source.
1 (b) Is chemical
potential energy a
source of energy?
Yes, it can be eg.
Food
( c) Can gravitational
potential energy be a
source of energy?
Yes, it can be. Water
in a reservoir behind
a dam.
2. Chemical Energy vs Chemical
Potential Energy
A bus uses CHEMICAL ENERGY to
move. (Or the bus uses chemical energy
stored in petrol.)
The petrol has CHEMICAL POTENTIAL
ENERGY.
The battery has chemical potential
energy.
----------------------Green leaf example:
Light energy  Chemical energy
The chemical energy is stored. The
energy stored in green leaves is chemical
Please get the terms right!
3. Gravitational Potential Energy =
Gravitational Energy ?
Gravitational Potential Energy =
Gravitational Force?
What is a force?
What is energy?
4. The use of ‘’ &
‘+’
(a) A falling stone posseses
Gravitational Potential Energy and
Kinetic Energy
Is it correct to write the following to
represent the above:
gravitational potential energy kinetic
energy
This statement is not about ENERGY
CONVERSION. It is asking about what
forms of energy a falling stone possesses / has.
4 (b) What
is the
difference?
Electrical energy 
Chemical energy +
heat energy
Electrical energy 
Chemical energy
Heat energy
OR
5.Any difference between the
following?
(a) Light vs Light Energy
(b) Sound vs Sound Energy
(c ) Heat vs Heat Energy
I see light at the end of the tunnel vs I see light
energy ….
The electrical energy in the electric train is
converted into…
Electrical energy kinetic energy+ light
energy+ heat energy+ sound energy
6. Energy ‘used up’? Correct?
When something is used up, it disappears.
In the case of Energy, it does not disappear,
it is transferred/ converted.
7. (a) A ball bounces
lower because it does
not have so much force.
A ball bounces because
it has energy. However,
it bounces lower and
lower because some
energy has been
transferred / converted
to sound energy and
heat energy.
BOUNCING
BALL
BOUNCING BALL
(b) It bounces lower because there is
friction. (air resistance?)
Friction slows down the movement of a
rolling ball…because of the surface of the
floor/ ground/ table with the ball. **
However, there is some air resistance.
BUT it is much less compared to a much
bigger surface area eg. A piece of paper
(same mass)
BOUNCING BALL
(c ) Gravitational force will also get
lower, therefore the ball bounces
lower. What is gravitational force?
(gravity)
(d) Gravitational potential energy acts
in the opposite direction of kinetic
energy. (gets pressurised?) Only
forces act in opposite directions.
LET’S NOW EXPLORE
DIFFERENT CONTEXTS
A
0.5 s
B
0.5 s
C
0.5 s
D
Diving
into the
pool
Solar powered structure
Roller Coaster
start
A
B car
bumper
D
C
E
water
F
finish
Weight-lifting
hitting
floor
lifted
falling
preparing
lifting
A
B
C
D
E
A
unstretched
length of the
rope
rope
Bungee
Jumping
B
C
D
water level