Energy Forms and Transformations

Forms of Energy

Mechanical Energy• Associated with the position and motion of an

object.• A combination of an object’s PE and KE (total

energy of the object at any one time)• An object with ME can do work on another

object. • ME = the ability to do work• The more ME, the more work an object can do

Calculating ME

• ME = PE + KE

• Sometimes an object’s ME is just its potential energy and sometimes it is just its kinetic energy.

At one point during the Super Bowl, the football had a GPE of

32 J and a KE of 45 J. What

was the ball’s ME?

• ME = PE + KE

• ME = 32J + 45J

• ME = 77J

Other Forms of Energy

• Potential, Kinetic, and Mechanical are 3 types of energy that deal with the motion and position of an object.

• There are several other types of energy that are associated with the particles of objects.

Thermal Energy• The particles that make up objects are called atoms

and molecules. They are always in motion.• The total kinetic and potential energy of the

molecules and atoms in an object is its thermal energy.

Friction

• Friction turns mechanical energy into thermal energy

• Energy “lost” due to friction still exists – it is now the energy of heat!

Electrical Energy

• Electrical energy results from the movement of charged particles.

• It can either be kinetic or potential depending on whether the charges are moving or stored.

Chemical Energy• Everything is made of

chemical compounds (which are made up of atoms and molecules bonded together).

• Chemical energy comes from the bonds of chemical compounds. Breaking and reforming those bonds releases and reorganizes energy.

• Example: Food!

Nuclear Energy• Stored in the nucleus

(center) of atoms… released during a nuclear reaction

• Nuclear Fission: Splitting the nucleus (Nuclear Power Plants electricity)

• Nuclear Fusion: Nuclei join together (Sun)

Electromagnetic Energy

• Travels in waves that have some electrical properties and some magnetic properties (hence the name!)

• All from the sun (although manmade machines can produce them as well)

• Examples: microwave, X-rays, radio wave, sunlight

*Law of Conservation of Energy*

• Energy cannot be created or destroyed

…but it can be transferred and transformed!

• The total amount of energy before any transformation is equal to the total amount of energy after

What’s the difference?

• Energy Transformation: Change from one form of energy to another form.

• Energy Transfer: Energy goes from one object to another as the same form.

Transform/Transfer Pictures

Transfer kinetic energy from player to ball

Chemical energy of food transformed to kinetic energy of boy

Transformations

• single transformation :

• toaster

• electrical energy to thermal energy

Transformations

• multiple transformations: a match

• Striking match (mechanical) causes friction (thermal) this releases the chemical energy in the match which creates fire (thermal and electromagnetic (light))

A Common Energy Transformation

• Kinetic Energy to Gravitational Potential Energy

• When does this happen?– When a basketball

is tossed up

– When a person jumps up and down

Gaining GPE

Losing KE

Gaining KE

Losing GPE