Download Energy Content from the Frameworks

Energy Content from State Frameworks and Other State Documents
Law of Conservation of Energy [included in other categories as well]


Energy is neither created nor destroyed but can be transformed.
Misconceptions: Energy gets used up or runs out; Energy is destroyed in
transformations from one type to another; Energy can be recycled. Proper Conception:
Energy is conserved. Energy is transformed from one form into another but it cannot
be recycled.
Potential and Kinetic Energy






Energy can exist in two forms: stored, called potential energy, or when it is associated
with motion, called kinetic energy.
Energy exists in two primary forms. Kinetic energy is the energy of motion. Potential
energy is stored energy that has the ― “potential” to do work.
Potential energy can be stored in foods. Foods release this energy when food is ―
“burned” by our bodies. This energy can be used by our bodies to do work.
Potential energy is stored energy.
One very important source of this energy is the energy stored in chemical bonds.
When the bonds are broken, the energy is released, and this energy can be used to do
work. One way to break these bonds is through a process called combustion – we
often refer to this as ―burning. A car uses combustion to release the energy in
chemical bonds of gasoline, and in the same way our cells use combustion to release
the energy stored in the chemical bonds of our food.
When energy is absorbed by the system, the atoms gain kinetic energy, potential
energy, or both. When energy leaves the system, the atoms lose kinetic energy,
potential energy, or both.
Forms of Energy







Energy appears in different forms such as mechanical energy, gravitational energy,
heat energy, and electric and magnetic energy.
Explain that electricity is the number one form of energy consumption. Explain that we
use available energy sources to create electricity in power plants.
You can’t see the energy in food, but when transformed into heat, it can be measured.
Misconception: Energy can be changed completely from one form to another (no
energy losses). Proper Conception: Typically in energy transformations, heat or light is
produced. Heat and light are unrecoverable energy forms. Energy can not be
recovered, but can be transformed into usable and non-usable forms.
Misconception: Energy is truly lost in many energy transformations. Proper
Conception: Energy is never lost. Rather, it changes to a form that is either useful
(usable) or unusable (energy losses).
Misconception: Heat and temperature are the same things. Proper Conception:
Temperature is a measure of the internal energy of the system. Heat is a form of
energy.
Misconception: The terms "energy" and "force" are interchangeable. Proper
Conception: Force is an action that causes an object to change its state of motion.
Mechanical energy is the ability of an object to do work. Energy in general is
something that is inherent in all matter and that is present in many different forms.
1
Energy Content from State Frameworks and Other State Documents

Why do skateboarders have to keep pushing with their feet? Answer: Friction between
the wheels and road and wheels and axles produce thermal energy which was
converted from kinetic energy. Therefore some kinetic energy is lost (transformed in
heat) and the speed will decrease.
Heat Transfer
















Transformations of energy usually release some energy typically in the form of heat.
Temperature changes as heat gets transferred.
Temperature changes as heat is transferred from a hotter object to a colder one.
Heat transfer occurs by conduction, convection, or radiation.
Energy is produced when two objects collide and rub against each other (kinetic
energy converts to thermal energy)
Heat may be transferred through matter (conduction), through space (radiation), or
through currents in fluids (convection).
Radiation is a method of heat transfer through any space by waves.
Heat transfer by conduction is the direct transfer or movement of warmth and energy
from one molecule to another molecule as a result of collisions between molecules.
Convection is the organized motion or movement of large groups of molecules based
on their relative densities or temperatures.
Heat from the sun moves by way of waves.
Radiation or heat waves pass most easily through a vacuum
In conduction, the hotter the substance, faster is the motion / movement of molecules
of the substance.
Convection occurs when warm air rises and cold air sinks causing circulation of heat.
When atoms rearrange themselves to make new substances, energy is often released
or absorbed. However, the total amount of energy before and after the change is
always the same.
Misconception: Cold can flow. Proper Conception: Energy flows. Energy always flows
from regions of high energy (high temperature) to regions of low energy (low
temperature).
Misconception: Heat and cold flow like liquids. Proper Conception: Heat is transferred
by molecular collisions or by absorption of radiant energy by molecules. The transfer
of heat happens either by conduction, radiation, or convection.
2
Energy Content from State Frameworks and Other State Documents
Other
















Energy is the ability to do work.
Without energy, forces cannot be generated to make things move or change.
Energy is involved in chemical and physical changes
Heat energy results due to the disorderly motion of molecules.
When matter undergoes change, it always involves energy moving into or out of the
system, often in the form of heat.
When heat energy is added, it changes the density of the air by adding energy to the
molecules. Explain that this is the same principle that causes the formation of wind
and ocean currents. Also, that air and water move because less dense hot air/water
rises up causing cool dense air/water to sink.
Mechanical waves are created when a source of energy causes a medium to vibrate.
We get energy from the compounds that make up our food.
Energy can be transferred by radiation, conduction, and convection.
As particles are exposed to increasing levels of energy, their speed of movement
increases and they will experience a change of phase
Every spontaneous process occurs in the direction of decreasing (lowering) the energy
of the system.
Misconception: All chemical and physical changes are exothermic. Proper Conception:
Energy is released when bonds form. Energy is absorbed when bonds are broken. In
exothermic reactions the products possess less energy than the reactants. Energy is
released when the bonds form, and energy is required for a bond to be broken.
Misconception: Something not moving can’t have any energy. Proper Conception:
Objects at rest have potential energy ―”stored energy”. Moving objects have kinetic
energy.
Misconception: Energy is a force. Proper Conception: Energy is the ability of an object
to do work. Force is an action that pushes or pulls an object.
Misconception: A cold body contains no heat. Proper Conception: Unless the object is
at absolute zero, its molecules are always oscillating and therefore it generates some
amount of heat energy.
Misconception: Sweaters will heat you up. Proper Conception: Sweaters help in
slowing down the rate of heat lost from your body by creating an insulation layer
between you and the cold air around you.
3