Science TAKS Need to Know 1 TAKS objective 4 Energy, Forces, and Motion Middle School Science...

Science TAKS Need to KnowScience TAKS Need to Know 11

TAKS objective 4TAKS objective 4Energy, Forces, and MotionEnergy, Forces, and Motion

Middle School ScienceMiddle School Science

Science TAKS Need to KnowScience TAKS 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


Specifics of Specific HeatSpecifics of Specific Heat

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?

Specific heat capacity of water is larger than soil,so the rise of temperature is less for water, all other things being equal. But, there's anothereffect:

Sun's energy penetrates farther into water thanit does into earth, so the temperature rise persquare meter of exposed surface is less forwater.

Water Holds Thermal Energy at Lower Temperature


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)


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


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


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.


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


A book resting on a desk illustrates balanced forces. However, a book dropped A book resting on a desk illustrates balanced forces. However, a book dropped from a desk illustrates unbalanced forces. In this case, gravity has from a desk illustrates unbalanced forces. In this case, gravity has overcome the balance of forces. overcome the balance of forces.


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.


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.


Data can be Data can be displayed & displayed &

interpreted in many interpreted in many waysways


Force & motion are relatedForce & motion are related


What’s the advantage to knowing how much force we use What’s the advantage to knowing how much force we use to do something???to do something???


A A leverlever is a bar that rests on a support is a bar that rests on a support called a fulcrum which lifts or moves called a fulcrum which lifts or moves loads. loads.


Types of leversTypes of levers


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.

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.


WedgeWedgeA wedge is an object with at least one slanting side ending in a sharp edge, which cuts material apart.


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 rampMountain road; Threaded screw.

The ancient Egyptians used inclined planes, or ramps, to move huge blocks of stone to build the pyramids.


A A screwscrew is an inclined plane is an inclined plane wrapped around a polewrapped around a pole


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

Science TAKS Need to Know 1 TAKS objective 4 Energy, Forces, and Motion Middle School Science...

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