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Types of
Energy
Mechanical energy:
Potential + Kinetic = Work
1. Work is done when a force acts on
an object to cause it to move, change
shape, displace, or do something
physical.
2. Mechanical energy is energy in
an object due to its motion, or
position, or both
3. In order for work to be done,
an object has to supply a
force for another object to be
displaced (moved from it’s place
Most potential
energy
Changing from
potential to kinetic energy
6. The hammer used both potential & kinetic
energy to drive the nail. Mechanical energy
results in work being done
Thermal (heat) Energy
Energy from the internal
motion of atoms
1. Thermal energy is energy that comes
from temperature of matter.
A swimming pool at 40°C is at a lower temperature than a cup of tea at 90°C.
However, the swimming pool contains a lot more water. Therefore, the pool has
more thermal energy than the cup of tea even though the tea is hotter than the
water in the pool.
Let us see this example below:
If we want to boil the water in these two beakers, we must increase their
temperatures to 100°C. You will notice that will take longer to boil the water in the
large beaker than the water in the small beaker. This is because the large beaker
contains more water and needs more heat energy to reach 100°C.
3 types of energy transfer:
• Conduction
• Convection
• radiation
Conduction:
the direct transfer of heat
from one substance to
another substance
that it is touching
3. Conduction: when a substance is
heated, its particles gain energy
and vibrate more vigorously.
The particles bump into nearby
particles and make them vibrate more.
For conduction to occur, the objects
must be touching
Convection:
the transfer of heat
by the movement of a
liquid or gas
4. Convection: when particles in liquids
and gasses get warm, they become less
dense (more loose) and they rise. The
space is quickly replaced by cooler
particles that are more dense.
Radiation:
The transfer of heat by
electromagnetic waves
5. Radiation: all objects transfer
thermal energy by infra-red
radiation. The hotter an object
is the more infra-red radiation
it gives off.
Chemical Energy:
Energy that is released
from chemical reactions –
when the bonds of atoms
are broken
1. Chemical energy is stored energy
in the bonds of chemical
compounds (atoms & molecules).
It is released in a chemical reaction.
3. The chemical energy stored in
food is measured in kilocalories
or calories.
4. How is the stored
chemical energy of coal released to
produce electricity?
By burning or boiling.
Electrical Energy:
Energy from the movement
of electrons.
1. Matter is made up of atoms. In these
atoms, there are even smaller stuff
called electrons that are constantly
moving.
2. We generate electrical energy
when we cause the electrons
to move from one atom to another
with the use of magnetic forces.
If you look at a battery, it will have two ends: a positive terminal and a negative terminal. If you
connect the two terminals with wire, a circuit is formed. Electrons will flow through the wire
and a current of electricity is produced.
3. What is one example of
electrical energy that
doesn’t need a wire?
Energy can be stored in many ways.
Then it can be transferred into other kinds of energy
Energy transfer:
a. The sun transfers thermal (heat)
energy to plants, humans & animals
b. Rivers, streams and waterfalls
are sources of water (hydro) energy
c. When humans eat plants, their
stored energy is transferred to us
and we use the energy to do work
d. The sun transfers heat energy to
bodies of water. The warm water
heats the air above it. The warm air
rises, so the air now is moving so it has
kinetic energy
e. Moving air (kinetic energy)
turns blades to generate wind
energy – which is used to
generate electrical energy
f. Energy from the sun (solar
energy) is captured and then
transferred to electrical energy
Energy Dissipation
1. As the pool ball is hit, the
kinetic energy decreases as
it moves along. 2. Kinetic energy
has been dissipated through friction