TAKS objective 4 Energy, Forces, and Motion

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TAKS objective 4Energy, Forces, and Motion

• Middle School Science
• Science TAKS Need to Know

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Energy

• The ability to do work or to cause change

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Chemical Energy Energy transformations
Chemical energy when light energy from the sun
is converted to the energy in the bonds of the
sugar molecules formed in photosynthesis.
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Chemical Energy

• Examples of chemical energy changing into heat
  energy
• Lighting a match
• Burning a wood fire

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Heat energy- Energy transformations

• Heat energy energy is absorbed and temperature
  rises.
• Specific heat- the ability of a substance to
  absorb heat energy

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Specifics of Specific Heat
Water Holds Thermal Energy at Lower Temperature
Temperature is a measure ofthe average kinetic
energyof the molecules in the object.-----------
------------------------------Will both fingers
feel the same temperature when they'reput in
the warm water?
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Electrical energy- Energy transformations
Electrical energy- flow of electrons (a current)

• Other ways of generating electricity
• Water flowing through a dam in a river to move
  turbines
• Wind generators that use the energy of moving
  wind operate a generator
• Nuclear power plants convert atomic energy into
  heat. Heat boils water to form steam then
  follows the same energy transformations as coal
  power plants

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Many energy transformations
Electrical to mechanical Electricity used to
spin the CD (Spinning CD has mechanical energy
due to its position or motion) Electrical to
sound A laser converts the digital information
on the CD into electrical energy and this energy
goes to the headphones as a vibration- this
transmits Sound! Chemical to electrical Batteries
store chemical compounds that react when they
are used to power something. This produces a
flow of electrons which is electricity!!
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Sound energy- Energy transformations
Sound consists of mechanical energy waves
created by vibrations. Sound must travel through
something (called medium or media) such as
air, water, or a solid. The medium carries the
energy of the wave from one place to another.
Example Air transmits the energy of the
vibrating material in the headphones to your
eardrums.
A vacuum is a space that contains little or no
matter. Sound cant travel through a vacuum
since there are no particles to squeeze together
(compression) or spread apart (rarefaction)
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• Many times it takes a whole series of energy
  conversions to do a certain job.
• For example, just to get the energy to make
  a piece of toast, there are several energy
  conversions involved.
• Chemical energy stored in coal is released as
  heat and light energy when the coal is burned.
  The heat energy is used to produce steam and is
  changed into mechanical energy in a generator.
  The generator converts mechanical energy into
  electrical energy that travels through power
  lines into your home. When you use your toaster,
  that electrical energy is again changed into heat
  energy.
• Have you ever touched a light bulb when it was
  on? Or tried to change it when it burnt out after
  being on? What you have discovered is the
  conversion process of energy- When you turn on a
  light, not all of the electricity is converted to
  light energy. Some of the energy is converted to
  heat.
• Remember, energy is never lost- its only
  converted from one form to another.
• This is the law of conservation of energy

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Light waves do not need a medium to transmit
energy! They can even travel through empty
space.
Light Waves
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Water waves are a form of a wave that transmits
mechanical energy across the surface of water.

• A wave is a disturbance that transfers energy
  from one place to another.

Water waves
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Seismic waves
Seismic waves are caused by earthquakes that
transmit mechanical energy through the Earths
layers.
San Andreas Fault
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Potential (PE)
Potential Energy
Stored energy
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Kinetic Energy (KE)
Energy due to motion of an object
Did you know that the gas burned in a car engine
is chemical energy being turned into Kinetic
Energy?
Kinetic energy
Speed mass affect kinetic energy Faster/heavier
more Kinetic Energy
Rubber band flying through the air has kinetic
energy
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• Before the yo-yo begins its fall it has stored
  energy due to its position. At the top it has its
  maximum potential energy. As it starts to fall
  the potential energy begins to be changed into
  kinetic energy. At the bottom its potential
  energy has been converted into kinetic energy so
  that it now has its maximum kinetic energy

A waterfall has both potential and kinetic
energy. The water at the top of Bridal Veil Falls
has stored potential energy. When the water
begins to fall, its potential energy is changed
into kinetic energy. This change in energy also
happens at Niagara Falls where it is used to
provide electricity from the transformation of
mechanical and electromagnetic energy.
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Energy Transformations

• Potential energy
• A rock sitting at the top of a cliff
• Roller coaster car at the top peak of a hill
• A swimmer posed to dive off the end of a diving
  board
• NO MOTION !!

• Kinetic energy
• A bouncing ball
• A moving roller coaster
• A track star running
• A girl skiing
• MOTION is the key!!!!

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Force pushing or pulling action that may change
motion
Forces may transfer energy between objects
Forces may MOVE objects
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• A book resting on a desk illustrates balanced
  forces. However, a book dropped from a desk
  illustrates unbalanced forces. In this case,
  gravity has overcome the balance of forces.

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You use force to move your body
When you bend your arm, your muscles contract,
which applies force to your arm bones. Your arm
responds to this force by moving.
During breathing, muscles contract (use force) to
move air in and out of the lungs.
The heart contracts (uses force) to pump blood
through the blood vessels, carrying oxygen to the
muscles.
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All living things use force to move
Plants exert force to open flower petals, curl
uncurl leaves push roots through the soil.
Emerging seedlings exert force on the surrounding
soil. This force pushes the stem of the plant out
of the ground.
Force is used to move materials in out of cells.
Fish exert force to swim by pushing against the
water.
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Balanced force
In order for a force to move something, it must
be an unbalanced force. This means that a force
is stronger in one direction than the forces in
the opposite direction.
Unbalanced force
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Let's look at some motion data
Acceleration of an object moving in one direction
is the speed (m/s) per unit of time (s), or
change in speed divided by time. The unit for
acceleration is m/s2.
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Data can be displayed interpreted in many ways
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Force motion are related
Force- measured in newtons ( N )
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Whats the advantage to knowing how much force we
use to do something???
It can help us make the work we do easier!
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• A lever is a bar that rests on a support called a
  fulcrum which lifts or moves loads. 

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Types of levers
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This pulley has 1 wheel, so it changes the
direction of pull 1 time. The input force is the
same as the weight using the pulley.
A pulley is a simple machine that uses grooved
wheels and a rope to raise, lower or move a load.
When a rope passes over a wheel, it changes the
direction of effort (pull) needed to move the
load.
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Wedge
A wedge is an object with at least one slanting
side ending in a sharp edge, which cuts material
apart.
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• An inclined plane is a ramp used to reduce the
  effort needed to raise or lower an object over a
  vertical height.
• It is easier to climb stairs to get to a second
  floor than to climb straight up a rope. It is
  easier to walk up a long, gentle hill than to
  climb up a short, steep hill.
• Examples of inclined planes
• Loading ramp Stairs or wheelchair ramp
• Mountain road Threaded screw.
• The ancient Egyptians used inclined planes, or
  ramps, to move huge blocks of stone to build the
  pyramids.

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• A screw is an inclined plane wrapped around a
  pole

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Wheel axle
A wheel with a rod, called an axle, through its
center lifts or moves loads.