Potential and Kinetic Energy

What is Energy? Energy – the ability to do work 2 categories of energy does NOT have mass or take up space Measured in the unit joules 2 categories of energy Potential Energy Kinetic Energy

Forms of Energy Energy can take different forms Potential Energy Kinetic Energy Chemical stored energy in bonds Thermal energy of moving particles (heat) Elastic stored energy due to tension Mechanical energy found in objects in motion Nuclear stored energy in the nucleus of an atom Electrical movement of electrons Gravitational stored energy due to position above ground Sound longitudinal waves that are heard EM Waves all the waves in the EM spectrum move

Law of Conservation of Energy Law of Conservation of Energy – no new energy is created nor destroyed, it’s just transferred from one form to another

Potential Energy Potential Energy – stored energy of position Has the “potential” to do something

Kinetic Energy Kinetic Energy – energy of motion

Energy Transformation When you lift the marble off the ground it gets potential energy because of its height

Energy Transformation As the marble moves down the track, it loses potential energy, and is converted into kinetic energy

Energy Transformation The marble slows down as it goes uphill because kinetic energy is being changed back into potential energy

Energy Transformation Animated Roller Coaster

Energy Conversion

Energy Conversion

Energy Conversion

Energy Conversion

What kind of energy transformations are occurring here?

Potential or Kinetic? Moving car Kinetic

Potential or Kinetic? Tree branch Potential

Bent car fender Potential Potential or Kinetic? Bent car fender Potential

Balloon filled with water Potential or Kinetic? Balloon filled with water Potential

Potential or Kinetic? Log of wood Potential

Balloon squirting around Potential or Kinetic? Balloon squirting around Kinetic

Person inside a moving car Potential or Kinetic? Person inside a moving car Kinetic

Potential or Kinetic? Both

Potential or Kinetic? Kinetic

Potential or Kinetic? Kinetic

An airplane circling in preparation for landing Potential or Kinetic? An airplane circling in preparation for landing Kinetic

A pile of coal that will be used for fuel Potential or Kinetic? A pile of coal that will be used for fuel Potential

An unlit firecracker Potential Potential or Kinetic? An unlit firecracker Potential

Glucose stored in plants as a result of photosynthesis Potential or Kinetic? Glucose stored in plants as a result of photosynthesis Potential

Burning log of wood Kinetic Potential or Kinetic? Burning log of wood Kinetic

A dam holding back a river’s water Potential or Kinetic? A dam holding back a river’s water Potential

A marble rolling down the aisle Potential or Kinetic? A marble rolling down the aisle Kinetic

A new car battery Potential Potential or Kinetic? A new car battery Potential

An ant crawling across a sandwich Potential or Kinetic? An ant crawling across a sandwich Kinetic

A tennis racket about to crash down on a ball Potential or Kinetic? A tennis racket about to crash down on a ball Potential

Energy at rest Potential Potential or Kinetic? Energy at rest Potential

A mousetrap set and ready to spring Potential or Kinetic? A mousetrap set and ready to spring Potential

PE= Joules (J)

Example An 80kg man is jogging at a rate of 4m/s. He has kinetic energy. Calculate it: KE = ½ x mass x velocity2 KE = ½ x 80kg x (4m/s)2 KE = ½ x 80 x 16 KE = 40 x 16 KE = 640 J

Example A 420kg boulder sits on top of a 100m cliff. What is the potential energy? PE=mgh PE = (420kg)(9.8 m/s2)(100M) PE=411,600 J