SIZE. Energy. Non-Mechanical Energy. Mechanical Energy. Part II. Examples of Non-Mechanical Energy. Examples of Mechanical Energy.

(1)

Energy Energy

Part II Part II

Non- Non -Mechanical Energy Mechanical Energy

Wait a minute Wait a minute……

…

…if all energy is either if all energy is either kinetic or potential kinetic or potential……

…

…and TME = KE + PEand TME = KE + PE

…

…then how can there then how can there possibly be such thing as possibly be such thing as

“

“nonnon--mechanical energymechanical energy””!?!?!?!?

Mechanical Energy Mechanical Energy

versus versus

Non Non- -Mechanical Energy Mechanical Energy

the difference between the difference between

them is all about them is all about

SIZE SIZE

_and_and

SCALE SCALE

Non- Non -Mechanical Energy Mechanical Energy

The energy of extremely small particles is not The energy of extremely small particles is not

considered mechanical energy.

But even the energy of But even the energy of these small particles can these small particles can be described as either be described as either

kinetic

kineticor or potentialpotential. .

…is the energy of particles or objects that are …is the energy of particles or objects that are too small to be seen

too small to be seen

Examples:

atoms, molecules, electrons, atoms, molecules, electrons, photons, protons, quarks, etc.

photons, protons, quarks, etc.

Examples of Mechanical Energy

Examples of Mechanical Energy Examples of Non- Examples of Non -Mechanical Energy Mechanical Energy

(2)

Non- Non - Mechanical Energy Mechanical Energy

Here are the other types Here are the other types of energy you should be of energy you should be able to recognize which able to recognize which are usually considered are usually considered

‘

‘nonnon--mechanicalmechanical’’:: THERMAL ENERGY THERMAL ENERGY ACOUSTIC ENERGY ACOUSTIC ENERGY CHEMICAL ENERGY CHEMICAL ENERGY NUCLEAR ENERGY NUCLEAR ENERGY ELECTRICAL ENERGY ELECTRICAL ENERGY RADIANT ENERGY RADIANT ENERGY

Thermal Energy (Heat) Thermal Energy (Heat)

Remember, Remember, heat is a form of heat is a form of kinetic energy kinetic energy……the the faster the

faster the molecules move, molecules move, the more heat the more heat energy is energy is produced.

produced.

= the kinetic energy of atoms or molecules

Thermal Energy (Heat) Thermal Energy (Heat)

A cooler object's molecules and A cooler object's molecules and atoms will show less movement.

atoms will show less movement.

= the kinetic energy of atoms or molecules

A hot object is one whose atoms A hot object is one whose atoms and molecules are excited and and molecules are excited and show rapid movement.

show rapid movement.

Thermal Energy (Heat) Thermal Energy (Heat)

Often, we say the mechanical energy of a system is “lost to friction”; but the energy

is still there -- it has just been converted into heat.

Acoustic Energy (Sound) Acoustic Energy (Sound)

(a mechanical wave is a disturbance (a mechanical wave is a disturbance pattern in a medium; in this case in the pattern in a medium; in this case in the pressure and density of particles of air) pressure and density of particles of air)

= the kinetic energy of mechanical waves which are audible the by human ear

Chemical Energy Chemical Energy

A form of potential energy, A form of potential energy, because it is stored, and because it is stored, and because it has to do

because it has to do wwithwwiththe the relative position of particles.

relative position of particles.

Examples:

–

– Digesting foodDigesting food……bonds are broken bonds are broken to release energy for your body to to release energy for your body to store and use.

store and use.

–– SportsSports……your body uses energy your body uses energy stored in your muscles obtained stored in your muscles obtained

= the energy stored in chemical bonds

(3)

Examples of Chemical Energy Examples of Chemical Energy

Nuclear Energy Nuclear Energy

When the nucleus of an atom splits, nuclear When the nucleus of an atom splits, nuclear energy is transformed to thermal energy.

energy is transformed to thermal energy.

Nuclear energy is the most concentrated Nuclear energy is the most concentrated form of energy.

form of energy.

Fission/fusion Fission/fusion

= the energy stored in the nucleus of an atom.

Electrical Energy Electrical Energy

Moving electrons have Moving electrons have

kinetic energy, stationary kinetic energy, stationary electrons have potential electrons have potential energy.

energy.

Electrical Potential Energy is Electrical Potential Energy is

called VOLTAGE.

Examples:

Power lines carry Power lines carry electricity electricity

Electric motors are driven Electric motors are driven by electromagnetic energy by electromagnetic energy

= the energy of electrons (can be kinetic or potential)

Radiant Energy (Light) Radiant Energy (Light)

Electromagnetic waves Electromagnetic waves are not waves in matter are not waves in matter like sound is; they can like sound is; they can travel through a travel through a vacuum.

vacuum.

May be visible or May be visible or invisible. (UV, radio, invisible. (UV, radio, ɣɣ)) Aka

Aka ‘‘radiationradiation’’

= the energy of electromagnetic waves

A B

1. What is the velocity of the coaster when it is at point A?

2. What is the KE of the coaster when it is at point A?

3. What is the height of the coaster when it is at point B?

4. What is the PE of the coaster when it is at point B?

Energy Energy

Part II

(4)

Energy Transformations Energy Transformations

and Conservation and Conservation

Energy Transformations Energy Transformations

What does flowing water have to do with What does flowing water have to do with electricity?

electricity?

You may already know that the mechanical You may already know that the mechanical energy of moving water can be transformed into energy of moving water can be transformed into electrical energy.

electrical energy.

Most forms of energy can be transformed into Most forms of energy can be transformed into other forms.

other forms.

A change from one form of energy to another is A change from one form of energy to another is called an

called an energy transformation.energy transformation. Some energy changes involve single Some energy changes involve single transformations, while others involve many transformations, while others involve many transformations.

transformations.

Single Transformations Single Transformations

Sometimes, one form of energy needs to be Sometimes, one form of energy needs to be transformed into another to get work done.

transformed into another to get work done.

You are already familiar with many such energy You are already familiar with many such energy transformations.

transformations.

For example, a toaster transforms electrical For example, a toaster transforms electrical energy to thermal energy to toast your bread.

energy to thermal energy to toast your bread.

A cell phone transforms electrical energy to A cell phone transforms electrical energy to electromagnetic energy that travels to other electromagnetic energy that travels to other phones.

phones.

Your body transforms the chemical energy Your body transforms the chemical energy in your food to mechanical energy you in your food to mechanical energy you need to move your muscles.

need to move your muscles.

Chemical energy in food is also Chemical energy in food is also

transformed to the thermal energy your transformed to the thermal energy your body uses to maintain its temperature.

body uses to maintain its temperature.

Figure 10:

Figure 10:Common Energy TransformationsCommon Energy Transformations Every day, energy transformations are all around Every day, energy transformations are all around you. Some of these transformations happen inside you. Some of these transformations happen inside

you!you!

Multiple Transformations Multiple Transformations

Often, a series of energy transformations Often, a series of energy transformations is needed to do work.

is needed to do work.

For example, the mechanical energy used For example, the mechanical energy used to strike a match is transformed first to to strike a match is transformed first to thermal energy.

thermal energy.

The thermal energy causes the particles in

the match to release stored chemical

energy, which is transformed to thermal

energy and the electromagnetic energy

(5)

In a car engine, another series of energy In a car engine, another series of energy conversions occurs.

conversions occurs.

Electrical energy produces a spark.

The thermal energy of the spark releases The thermal energy of the spark releases chemical energy in the fuel.

chemical energy in the fuel.

The fuel

The fuel’ ’s chemical energy in turn s chemical energy in turn becomes thermal energy.

becomes thermal energy.

Thermal energy is converted to Thermal energy is converted to

mechanical energy used to move the car, mechanical energy used to move the car, and to electrical energy to produce more and to electrical energy to produce more sparks.

sparks.

Transformations Between Potential Transformations Between Potential

and Kinetic Energy and Kinetic Energy

One of the most common energy One of the most common energy

transformations is the transformation between transformations is the transformation between potential energy and kinetic energy.

potential energy and kinetic energy.

In waterfalls such as Niagara Falls, potential In waterfalls such as Niagara Falls, potential energy is transformed to kinetic energy.

energy is transformed to kinetic energy.

The water at the top of the falls has gravitational The water at the top of the falls has gravitational potential energy.

potential energy.

As the water plunges, its velocity increases.

Its potential energy becomes kinetic energy.

Energy Transformation in Juggling Energy Transformation in Juggling

Any object that rises or falls Any object that rises or falls experiences a change in its experiences a change in its kinetic and gravitational kinetic and gravitational potential energy.

potential energy.

Look at the orange in Look at the orange in Figure Figure 11

11. .

When it moves, the orange When it moves, the orange has kinetic energy.

has kinetic energy.

As it rises, it slows down.

Its potential energy increases Its potential energy increases as its kinetic energy

as its kinetic energy decreases.

decreases.

At the highest point in its At the highest point in its path, it stops moving.

path, it stops moving.

Since there is no motion, Since there is no motion, the orange no longer has the orange no longer has kinetic energy.

kinetic energy.

But it does have potential But it does have potential energy.

energy.

As the orange falls, the As the orange falls, the energy transformation is energy transformation is reversed.

reversed.

Kinetic energy increases Kinetic energy increases while potential energy while potential energy decreases.

decreases.

Energy Transformation in a Energy Transformation in a

Pendulum Pendulum

In a pendulum, a continuous transformation between In a pendulum, a continuous transformation between kinetic and potential energy takes place.

kinetic and potential energy takes place.

At the highest point in its swing, the pendulum in At the highest point in its swing, the pendulum in Figure 12Figure 12 has no movement, so it only has gravitational potential has no movement, so it only has gravitational potential energy.

energy.

As it swings downward, it speeds up.

Its potential energy is transformed to kinetic energy.

The pendulum is at its greatest speed at the bottom of its The pendulum is at its greatest speed at the bottom of its swing.

swing.

There, all its energy is kinetic energy.

As the pendulum swings to the other side, its height As the pendulum swings to the other side, its height increases.

increases.

The pendulum regains gravitational potential energy and The pendulum regains gravitational potential energy and loses kinetic energy.

loses kinetic energy.

At the top of its swing, it comes to a stop again.

And so the pattern of energy transformation continues.

(6)

Energy Transformation in a Pole Energy Transformation in a Pole

Vault Vault

A pole

A pole--vaulter transforms vaulter transforms kinetic energy to elastic kinetic energy to elastic potential energy, which potential energy, which then becomes then becomes gravitational potential gravitational potential energy.

energy.

The pole

The pole--vaulter you see vaulter you see in

in Figure 13Figure 13has kinetic has kinetic energy as he runs energy as he runs forward.

forward.

When the pole When the pole--vaulter vaulter plants the pole to jump, plants the pole to jump, his velocity decreases his velocity decreases and the pole bends.

and the pole bends.

His kinetic energy is transformed to elastic potential energy in His kinetic energy is transformed to elastic potential energy in the pole.

the pole.

As the pole straightens out, the pole

As the pole straightens out, the pole--vaulter is lifted high into vaulter is lifted high into the air.

the air.

The elastic potential energy of the pole is transformed to the The elastic potential energy of the pole is transformed to the gravitational potential energy of the pole

gravitational potential energy of the pole--vaulter. vaulter.

Once he is over the bar, the pole

Once he is over the bar, the pole--vaultervaulter’’s gravitational s gravitational potential energy is transformed back into kinetic energy as he potential energy is transformed back into kinetic energy as he falls toward the safety cushion.

falls toward the safety cushion.

Conservation of Energy Conservation of Energy

If you set a spinning top in motion, will the top If you set a spinning top in motion, will the top remain in motion forever?

remain in motion forever?

No, it will not.

Then what happens to its energy?

Is the energy destroyed?

Again, the answer is no.

The

The law of conservation of energylaw of conservation of energystates that states that when one form of energy is transformed to when one form of energy is transformed to another, no energy is destroyed in the process.

another, no energy is destroyed in the process.

According to the law of conservation of According to the law of conservation of energy, energy cannot be created or energy, energy cannot be created or destroyed.

destroyed.

So the total amount of energy is the same So the total amount of energy is the same before and after any transformation.

before and after any transformation.

If you add up all the new forms of energy If you add up all the new forms of energy after a transformation, all of the original after a transformation, all of the original energy will be accounted for.

energy will be accounted for.

Energy and Friction Energy and Friction

So what happens to the energy of So what happens to the energy of the top in

the top in Figure 14Figure 14? ?

As the top spins, it encounters friction with the floor As the top spins, it encounters friction with the floor and friction from the air.

and friction from the air.

Whenever a moving object experiences friction, Whenever a moving object experiences friction, some of its kinetic energy is transformed into some of its kinetic energy is transformed into thermal energy.

thermal energy.

So, the mechanical energy of the spinning top is So, the mechanical energy of the spinning top is transformed to thermal energy.

transformed to thermal energy.

The fact that friction transforms mechanical The fact that friction transforms mechanical energy to thermal energy should not surprise energy to thermal energy should not surprise you.

you.

After all, you take advantage of such thermal After all, you take advantage of such thermal energy when you rub your cold hands together energy when you rub your cold hands together to warm them up.

to warm them up.

The fact that friction transforms mechanical The fact that friction transforms mechanical energy to thermal energy explains why no energy to thermal energy explains why no machine is 100

machine is 100percent efficient. percent efficient.

You may recall that the output work of any real You may recall that the output work of any real machine is always less than the input work.

machine is always less than the input work.

This reduced efficiency occurs because some This reduced efficiency occurs because some mechanical energy is always transformed into mechanical energy is always transformed into

(7)

Energy and Matter Energy and Matter

You might have heard of Albert Einstein

You might have heard of Albert Einstein’’s theory s theory of relativity.

of relativity.

His theory stated that energy

His theory stated that energy cancansometimes be sometimes be created

created——by destroying matter! by destroying matter!

Matter

Matteris anything that has mass and takes up is anything that has mass and takes up space.

space.

All objects are made up of matter.

Just as one form of energy can be transformed Just as one form of energy can be transformed to other forms, Einstein discovered that matter to other forms, Einstein discovered that matter can be transformed to energy.

can be transformed to energy.

In fact, destroying just a small amount of matter In fact, destroying just a small amount of matter releases a huge amount of energy.

releases a huge amount of energy.

Einstein

Einstein’’s discovery meant s discovery meant that the law of conservation that the law of conservation of energy had to be of energy had to be adjusted.

adjusted.

In some situations, energy In some situations, energy alone is not conserved.

alone is not conserved.

However, since matter can However, since matter can be transformed to energy, be transformed to energy, scientists say matter and scientists say matter and energy together are always energy together are always conserved.

conserved.

Einstein published his theory of special relativity in 1905.

QUIZ TIME!

What type of energy What type of energy

cooks food in a cooks food in a microwave oven?

microwave oven?

ELECTROMAGNETIC ELECTROMAGNETIC

ENERGY ENERGY What type of energy is What type of energy is

the spinning plate the spinning plate inside of a microwave inside of a microwave oven?

oven?

MECHANICAL ENERGY MECHANICAL ENERGY

QUIZ TIME!

Electrical energy is Electrical energy is

transported to your house transported to your house through power lines.

through power lines.

When you plug an electric fan When you plug an electric fan to a power outlet, electrical to a power outlet, electrical energy is transform into energy is transform into what type of energy?

what type of energy?

MECHANICAL ENERGY MECHANICAL ENERGY

QUIZ TIME!

What energy transformation What energy transformation occurs when an electric lamp occurs when an electric lamp

is turned on?

ELECTRICAL ENERGY ELECTRICAL ENERGY

 

ELECTROMAGNETIC ENERGY ELECTROMAGNETIC ENERGY

What types of energy are shown below?

Mechanical and Thermal Energy Mechanical and Thermal Energy

(Don ( Don’ ’t forget friction t forget friction) )

(8)

What type of energy is shown below?

Chemical Energy Chemical Energy

What types of energy are shown below?

Electrical, Mechanical and Electrical, Mechanical and Electromagnetic Energy Electromagnetic Energy

What type of energy is shown below?

Chemical Energy (yummy) Chemical Energy (yummy)

What type of energy is shown below?

Thermal Energy Thermal Energy

Draw a flow map showing the flow of

energy transformations in a car from

starting vehicle to driving. You should

have 5 different types of energy.

Energy Transfer Energy Transfer

Chemical

Electrical Electrical

Electrica l

Sound (mechanical)

Thermal

Mechanical