Energy

What is Energy? The ability to make things move/cause change or to do work Any change Every change that occurs involves energy….changes REQUIRE energy SI Unit – Joule ( J )

Work The transfer of energy from one object to another Work is when a force moves an object Also SI unit: Joule (J) Energy is the ability to do work. You are doing work. Your pencil is doing work. Both of you have energy.

Can you make things move? Then you have energy… …but there are many different kinds of energy…

Curriculum Connection Everything we learn this year is connected in some way and we learn it in a logical order. Think back to our previous units: How is energy related to (or how does it build upon what we already learned about) motion and forces?

Review Slide What is the SI unit for each quantity? Write in your comp book – help each other if you need to. Force Height Work Mass Energy

Chemical Energy What holds atoms in molecules together Has the “potential” to be released by chemical reactions like burning wood FOOD (CPE)

What is Chemical Energy? Energy that is available for release from chemical reactions. The chemical bonds in a matchstick store energy that is transformed into thermal energy when the match is struck.

Examples of Chemical Energy

Electrical Energy The movement (KE) of electrons through conductive matter newly derived from electrical PE Electricity is a form of electrical energy

What is Electrical Energy? Energy caused by the movement of electrons Easily transported through power lines and converted into other forms of energy

Thermal Energy (HEAT) The random motion, or vibration, of atoms in matter The faster the atoms vibrate the more heat energy they have How we measure temperature

What is Thermal Energy? Heat energy The heat energy of an object determines how active its atoms are. A hot object is one whose atoms and molecules are excited and show rapid movement. A cooler object's molecules and atoms will show less movement.

Light/Radiant Energy The energy carried by light Yes, whenever you are looking at light, you are looking at energy

What is Electromagnetic Energy? Light energy Includes energy from gamma rays, xrays, ultraviolet rays, visible light, infrared rays, microwave and radio bands

Mechanical Energy The total energy of moving things PE + KE = ME When you ride a bike you use mechanical energy Anytime you or an object does work.

What is Mechanical Energy? Energy due to a object’s motion (kinetic) or position (potential). The bowling ball has mechanical energy. When the ball strikes the pins, mechanical energy is transferred to the pins!

Examples of Mechanical Energy

Nuclear Energy Holds protons and neutrons together in an atom’s nucleus Atoms can split (nuclear fissure) or fuse together (nuclear fusion) Powers the sun and nuclear power plants

Sound Energy Vibrates air molecules The air molecules move tiny bones in your ear The message of sound then moves to your brain Can also vibrate objects

Energy Transformations When one form of energy changes to another form, this is called an energy transformation. Energy transformations occur most often between potential and kinetic energy.

Potential to Kinetic Falling objects- at the top of the hill, the ball has potential energy. As it rolls down the hill, its potential energy decreases, but as it gains speed its kinetic energy increases.

Energy can be transformed from one form to another Chemical energy in gasoline is changed to heat energy and then to mechanical energy in a car

Energy can be transformed from one form to another When you eat, your body converts the chemical energy in food into thermal energy.

QUIZ TIME! Electrical energy is transported to your house through power lines. When you plug an electric fan to a power outlet, electrical energy is transform into what type of energy? MECHANICAL ENERGY

QUIZ TIME! What energy transformation occurs when an electric lamp is turned on? ELECTRICAL ENERGY  ELECTROMAGNETIC/RADIANT ENERGY

What types of energy are shown below? Mechanical and Thermal Energy (Don’t forget friction)

What type of energy is shown below? Chemical Energy (CPE)

What types of energy are shown below? Electrical, Mechanical and Electromagnetic/Radiant Energy

What type of energy is shown below? Chemical Energy (yummy)

What type of energy is shown below? Thermal Energy

Energy Transfer Sound (mechanical) Electrical Thermal Mechanical Chemical Electrical Light (Electromagnetic)

Power The rate energy is transformed. (Rate work is done) The more power something has, the quicker the energy transforms. Example) a runner running burns energy more quickly than someone walking, therefore they have more power Can you think of another example?

What is the difference?

Kinetic energy: energy of a moving object because of its motion (Depends on MASS and SPEED) Potential energy: stored energy due to its position “Has the potential to move”

Kinetic = moving [falling apple] potential = stored (not moving) The apple has the ability to cause change…therefore, it has energy If the apple stays in the tree, the energy is stored as potential energy, if it falls, there is a change of motion (kinetic energy)

TYPES OF POTENTIAL ENERGY Elastic Potential Energy - energy stored by something that can stretch or compress (like a rubber band or a spring) The stretching of the rubber band shows elastic pot. Energy – it flying through air is kinetic Gravitational Potential Energy (GPE) – the stored energy for anything that can fall (the energy stored by objects due to their position above the Earth’s surface Depends on the MASS & HEIGHT ABOVE GROUND

Which Type?

Which Type?

Which Type?

Law of Conservation of Energy As energy is transformed, it is neither created or destroyed. It stays the same. It is conserved. The amount of energy in the entire universe is always the same. It just transforms into different forms. (Friction can absorb some of the energy, but it doesn’t destroy it)

Which type of energy. How is this the Conservation of Energy Which type of energy? How is this the Conservation of Energy? Why does it eventually stop?

Both Potential and Kinetic. The friction eventually slows it down Both Potential and Kinetic. The friction eventually slows it down. Friction causes the energy to transform to thermal (heat) energy. Kinetic energy and potential combined make thermal energy.

RECAP: -The amount of energy in the Universe never changes. It just transforms (changes into different forms). The Law of Conservation of Energy. -There are two main types of energy: Kinetic (motion) and Potential (has the potential for motion) -There are many other forms of energy that can transform into each other. -The unit for energy is the joule and energy is simply the ability for something to change.