1 objective 4 energy, forces, and motion middle school science science staar need to know

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Objective 4Objective 4Energy, Forces, and MotionEnergy, Forces, and Motion

Middle School ScienceMiddle School Science

Science STAAR Need to KnowScience STAAR Need to Know

22Science TAKS Need to KnowScience TAKS Need to Know

EnergyEnergy

The ability to do The ability to do work work oror to cause to cause

changechange


Chemical Energy – Chemical Energy – Energy transformationsEnergy transformations

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


Chemical EnergyChemical Energy

Examples of chemical Examples of chemical energy changing into energy changing into heat energy:heat energy:

Lighting a matchLighting a match

Burning a wood fireBurning a wood fire


Heat energy- Heat energy- Energy transformationsEnergy transformations

Heat energy – energy is absorbed and temperature rises.

Specific heat- the ability of a substance to absorb heat energy


Electrical energy- Electrical energy- Energy transformationsEnergy 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


Many energy transformations…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!!


Sound energy- Sound energy- Energy transformationsEnergy 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 can’t 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. 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 For example, just to get the energy to make a piece of toast, there are several

energy conversions involved. energy conversions involved.

Chemical energyChemical energy stored in coal is released as stored in coal is released as heat and light energyheat and light energy when the coal when the coal is burned. The is burned. The heat energyheat energy is used to produce steam and is changed into is used to produce steam and is changed into mechanical energymechanical energy in a generator. The generator converts in a generator. The generator converts mechanical energymechanical energy into into electrical energyelectrical energy that travels through power lines into your home. When you use that travels through power lines into your home. When you use your toaster, that your toaster, that electrical energyelectrical energy is again changed into is again changed into heat energyheat energy. .

Have you ever touched a light bulb when it was on? Or tried to change it when it 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 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- When you turn on a light, not all of the electricity is converted to light energy. Some of the energy is converted to heat. energy. Some of the energy is converted to heat.

Remember, energy is never lost- it’s only converted from one form to another. Remember, energy is never lost- it’s only converted from one form to another.

This is the This is the law of conservation of energylaw of conservation of energy


Light waves do not need a medium to transmit energy! They can even travel through empty space.


Water waves are a form of a wave that transmits mechanical energy across the surface of water.

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


Seismic waves are caused by earthquakes that transmit mechanical energy through the Earth’s layers.


Potential (PE)Potential (PE)

Stored energy


Before the yo-yo begins its fall it has stored energy due to its 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 position. At the top it has its maximum potential energy. As it starts to fall the potential energy begins to be changed into kinetic starts to fall the potential energy begins to be changed into kinetic energy. At the bottom its potential energy has been converted energy. At the bottom its potential energy has been converted into kinetic energy so that it now has its maximum kinetic energyinto kinetic energy so that it now has its maximum kinetic energy

A waterfall has both potential and A waterfall has both potential and kinetic energy. The water at the top kinetic energy. The water at the top of Bridal Veil Falls has stored of Bridal Veil Falls has stored potential energy. When the water potential energy. When the water begins to fall, its potential energy is begins to fall, its potential energy is changed into kinetic energy. changed into kinetic energy.

This change in energy also This change in energy also happens at Niagara Falls where it is happens at Niagara Falls where it is used to provide electricity from the used to provide electricity from the transformation of mechanical and transformation of mechanical and electromagnetic energy.electromagnetic energy.


Kinetic Energy (KE)Kinetic Energy (KE)

Energy due to motion of an object

Speed & mass affect kinetic energy–

Faster/heavier…more Kinetic Energy

Did you know that Did you know that the gas burned in a the gas burned in a car engine is car engine is chemical energy chemical energy being turned into being turned into Kinetic Energy?Kinetic Energy?

Rubber band flying through the air has kinetic energy


Energy TransformationsEnergy Transformations

Potential energyPotential energy

A rock sitting at the A rock sitting at the top of a clifftop of a cliff

Roller coaster car at Roller coaster car at the top peak of a the top peak of a hillhill

A swimmer posed to A swimmer posed to dive off the end of dive off the end of a diving boarda diving board

NO MOTION !!NO MOTION !!

Kinetic energyKinetic energy

A bouncing ballA bouncing ball

A moving roller A moving roller coaster coaster

A track star A track star runningrunning

A girl skiingA girl skiing

MOTION is the MOTION is the key!!!!key!!!!


Forces may MOVE objects

Forces may transfer

energy between objects


You use force to move your bodyYou use force to move your bodyWhen 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.


All living things use force to moveAll living things use force to move

Emerging seedlings exert force on the surrounding soil.

This force pushes the stem of the plant out of the ground.

Plants exert force to open flower petals, curl & uncurl leaves & push roots through the soil.

Force is used to move materials in & out of cells.

Fish exert force to swim by pushing against the water.


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.

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Speed involves distance & time

Average speed – can be calculated by dividing total distance by total time.

S= D/T

Instantaneous speed – an object’s speed at a specific moment When instantaneous speed does not change, an object is moving at constant speed; in this situation average speed and instantaneous speed are the same.

Speed and direction of motion is velocity.

Acceleration is the change in velocity divided by the time it takes for the change to happen. It can be a change in speed or a change in direction or both. Acceleration can be calculated using this formula: a = ( final speed - initial speed ) time

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Acceleration can be shown on a speed-time graph.

A change in speed is a change in velocity – so, a change in speed is an example of acceleration! Acceleration may be positive or negative. Negative acceleration is sometimes called deceleration.


Data can be Data can be displayed & displayed &

interpreted in many interpreted in many waysways

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The energy transferred when a force moves an object or changes its shape

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Newton’s 1st law – states an object at rest will stay at rest unless acted on by an unbalanced force. An object in motion will stay in motion at the same speed and direction unless acted on by an unbalanced force.

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- a moving object moves in a straight line with constant speed unless a force acts on it.

- An object will not start moving unless a force acts on it - An object will not stop moving unless a force acts on it - An object will not change speed unless a force acts on it -An object will not change direction unless a force acts on it

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Acceleration can be calculated as Acceleration = force/mass

~or~ Force = mass X acceleration

The more mass an object has the more force it takes to cause acceleration. - Big masses are hard to accelerate. - Small masses are easy to accelerate. - Objects accelerate more quickly when a greater force is used.

2nd law states that the acceleration of an object depends on its mass and the size and direction of the force acting on it.

1 objective 4 energy, forces, and motion middle school science science staar need to know

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light energy

atomic energy

mechanical energy waves

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series of energy conversions

energy of moving wind

conversion process of

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