Ch.9, Sec.1 – What Is Energy?

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# Ch.9, Sec.1 – What Is Energy? - PowerPoint PPT Presentation

Energy and Work: Working Together. energy : the capacity to do work. Ch.9, Sec.1 – What Is Energy?. work is done when a force causes an object to move in the direction of the force. when one object does work on another, energy is transferred from the 1st object to the 2nd.

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Presentation Transcript

Energy and Work: Working Together

• energy: the capacity to do work

### Ch.9, Sec.1 – What Is Energy?

• work is done when a force causes an object to move in the direction of the force
• when one object does work on another, energy is transferred from the 1st object to the 2nd
• therefore, work is a transfer of energy!
• energy is expressed in units of Joules (J)

- all matter has atoms; therefore, all matter has energy!!!!!

Ch.9, Sec.1 – What Is Energy?
• Kinetic Energy
• kinetic energy: the energy of motion
• all moving objects have kinetic energy & this energy can be used to do work
• kinetic energy can be found using the following formula:

KE = mv²

2

- m stands for mass in kilograms, v stands for the objects speed (the more speed & mass of an object means greater kinetic energy)

• speed has a greater effect on kinetic energy than mass (faster cars cause greater crashes)
Ch.9, Sec.1 – What Is Energy?
• Potential Energy
• potential energy: the energy that an object has because of the position, shape, or condition of the object
• any object elevated from the ground has gravitational potential energy (the more weight & height means greater GPE)

- gravitational potential energy can be found using the following formula:

GPE = weight x height

• GPE is expressed using Newton-meters
• height of GPE is a measure of how far an object has to fall
Ch.9, Sec.1 – What Is Energy?
• Mechanical Energy
• mechanical energy: the total energy of motion and position of an object (can be all potential, all kinetic, or some of each)
• mechanical energy can be found using the following formula:

ME = PE + KE

• mechanical energy remains the same unless it transfers some of its energy to another object
• even if mechanical energy stays the same, potential or kinetic energy can increase or decrease
Ch.9, Sec.1 – What Is Energy?
• Other Forms of Energy
• thermal energy: all of the kinetic energy due to random motion of the particles that make up an object
• there’s more kinetic energy in gases than solids because of the molecular movement
Ch.9, Sec.1 – What Is Energy?
• chemical energy: the energy of a compound that changes as its atoms are rearranged

- chemical energy is a form of potential energy because it depends on the position & arrangement of the atoms in the compound

Ch.9, Sec.1 – What Is Energy?
• electrical energy: the energy of moving electrons

- changing positions of magnets at power plants provides electrical energy (potential energy too)

Ch.9, Sec.1 – What Is Energy?
• sound energy: the energy caused by an object’s vibrations (potential energy turned into kinetic energy)
• light energy: energy produced by the vibrations of electrically charged particles
• light energy can travel through a vacuum! (an area with little or no atoms, like deep space)
Ch.9, Sec.1 – What Is Energy?
• nuclear energy: the energy that comes from changes in the nucleus of an atom
• energy can be from fusion where atoms can join together to create electrical energy (Sun)

- energy can be from fission where atoms can be split apart in the nucleus to create a lot of potential energy (uranium in the atomic bombs)