unit 2 lesson 1 introduction to energy copyright © houghton mifflin harcourt publishing company

Unit 2 Lesson 1 Introduction to Energy

Copyright © Houghton Mifflin Harcourt Publishing Company

Get Energized!


What are two types of energy?

• Energy is the ability to cause change.

• Energy takes many different forms and causes many different effects.

• There are two general types of energy: kinetic energy and potential energy.



• Kinetic energy is the energy of an object that is due to motion. All moving objects have kinetic energy.

• The amount of kinetic energy an object has depends on its mass and speed.

• Kinetic energy increases as mass increases and as speed increases.




• Potential energy is the energy that an object has due to its position, condition, or chemical composition.

• Potential energy that is the result of an object’s position is called gravitational potential energy.

• Gravitational potential energy increases as the object’s height or mass increases.




• A change in the condition of an object affects its potential energy. Stretching a rubber band increases its potential energy.

• Chemical potential energy depends on chemical composition.

• As bonds break and new bonds form between atoms during a chemical change, energy can be released.



Can objects have potential and kinetic energy at the same time?• An object can have both potential and kinetic

energy at the same time.

• A skater has kinetic energy as he moves down a ramp and potential energy due to his position on the ramp.



In Perfect Form


What forms can energy take?

• Kinetic energy and potential energy are two types of energy that can come in many different forms.

• Some common forms of energy include mechanical, sound, electromagnetic, electrical, chemical, thermal, and nuclear energy.

• Energy is expressed in joules (J).



• Mechanical energy is the sum of an object’s kinetic energy and potential energy. It is the energy of position and motion.

• Sound energy is kinetic energy caused by the vibration of particles in a medium such as steel, water, or air.




• Electromagnetic energy is transmitted through space in the form of electromagnetic waves.

• These waves are caused by the vibration of electrically charged particles.

• Electromagnetic waves include visible light, X-rays, and microwaves.




• Electrical energy is the energy that results from the position or motion of charged particles.

• Chemical energy is a form of potential energy.

• The amount of chemical energy in a molecule depends on the kinds of atoms and their arrangement.




• The thermal energy of an object is the kinetic energy of its particles.

• The faster the molecules in an object move, and the more particles the object has, the more thermal energy it has.

• Heat is the energy transferred from an object at a higher temperature to an object at a lower temperature.




• The nucleus of an atom is the source of nuclear energy.

• When an atom’s nucleus breaks apart, or when the nuclei of two small atoms join together, energy is released.




Space Weather and Technology


• Space weather includes any activity happening in space that might affect Earth’s environment.

• Space weather can damage satellites and interrupt phone signals and signals to Global Positioning System (GPS) receivers.

• Auroras are caused by electrically charged particles of solar winds hitting Earth’s magnetic field. They can interrupt airplane communications.

Transformers


What is an energy transformation?

• An energy transformation takes place when energy changes from one form into another form.

• Any form of energy can change into any other form of energy.

• Often, one form of energy changes into more than one form.


What is an energy transformation?

• In a flashlight, chemical energy is transformed into electrical energy.

• The electrical energy is then transformed into light and thermal energy.



Is energy conserved?

• A closed system is a group of objects that transfer energy only to one another. Energy is conserved in all closed systems.

• The law of conservation of energy states that energy cannot be created or destroyed. It can only change forms.

• All of the different forms of energy in a closed system always add up to the same total amount of energy.



Unit 2 Lesson 2 Temperature


Particle Party


What is the kinetic theory of matter?

• The kinetic theory of matter states that all of the particles that make up matter are constantly in motion.

• Because the particles are in motion, they have kinetic energy.

• The faster they move, the more kinetic energy they have.


What is the kinetic theory of matter?

• The motion of the particles is random.

• The individual particles have different amounts of kinetic energy, but their average kinetic energy takes into account their different random motions.

• Solids, liquids, and gases have different average kinetic energies.



How do particles move in solids, liquids, and gases?• The kinetic theory of matter explains the motion of

particles in solids, liquids, and gases.

• The particles in a solid do not move around much.



How do particles move in solids, liquids, and gases?• The particles in a liquid move much more freely

than the particles in a solid. They slide past and tumble over each other.



How do particles move in solids, liquids, and gases?• The particles in a gas are far apart, move at high

speeds, and collide with one another.



Mercury Rising


How does temperature relate to kinetic energy?• Temperature is a measure of the average kinetic

energy of all the particles in an object.

• The warmer a substance is, the faster its particles move.


How is temperature measured?

• There are three common temperature scales.

• They all measure the average kinetic energy of particles.

• The scales are called Celsius, Fahrenheit, and Kelvin.




• In the Celsius and Fahrenheit scales, temperature is measured in units called degrees.

• Degrees (°) are equally spaced units between two points. The space between degrees can vary from one scale to another.

• In the Kelvin scale, no degree sign is used. The unit is just called a kelvin.

• Temperature is measured with a thermometer.




• The Celsius scale is the temperature scale most commonly used around the world.




• The Fahrenheit scale is used most commonly in the United States.




• The Kelvin scale is used most commonly by physicists.



unit 2 lesson 1 introduction to energy copyright © houghton mifflin harcourt publishing company

Documents

chemical energy

energy of position

electromagnetic energy

sound energy

mechanical energy

electrical energy

nuclear energy

chemical potential energy