Unit PEF: Potential Energy and Fields

action-at-a-distance interaction

push/pull interaction between two objects without touching (ex: magnetic/electric/gravitational)

electromagnetic interactions

- situations in which electric charges and magnets affect each other

- electric charges always have an electric field around them, but when they are moving (electric current) a magnetic field is created.

- magnets have a magnetic field around them, but when they are moving they create an electric field

magnetic field

- invisible 'force-field' in area around a magnet

- used to explain 'action-at-a-distance' aspect of interactions between magnets

- only detectable when it causes a push or pull on another magnet

- stores MPE

electro"static" field

- used to explain 'action-at-a-distance' aspect of interactions between charges

- only detectable when it causes a push or pull on another charge

- stores SPE

gravitational field

- used to explain 'action-at-a-distance' aspect of interactions between masses

- only detectable when it causes a push or pull on another mass

- stores GPE

elastic potential energy (EPE)

stored when stretchy objects are stretched or springy objects are compressed

increases

when a stretchy object becomes more stretched (or a springy object becomes more compressed) its EPE ______________.

decreases

when a stretchy object becomes less stretched (or a springy object becomes less compressed) its EPE ______________.

magnetic potential energy (MPE)

stored in magnetic field

gravitational potential energy (GPE)

stored in gravitational field

greater

the greater the distance an object is from Earth, the _____________ the GPE.

decrease in energy of object(s) = increase in energy of object(s)

statement of conservation of energy

giver

a magnetic/electric/gravitational field can be an energy ________ if its PE decreases.

receiver

a magnetic/electric/gravitational field can be an energy ________ if its PE increases.

more; less

kinetic energy depends on both speed and mass. if given the same amount of energy, an object with ______ mass will show less change in speed compared to an object with _____ mass.

KE of Earth

objects fall towards Earth and Earth falls towards objects, but the mass of Earth is so big that the change in __________________ is imperceptible.

gravitational interaction

the "action-at-a-distance" interaction where a falling object increases its speed as it falls and is not touching another object

increases

for two objects at a distance that attract each other, the potential energy of the (magnetic/electric/gravitational) field _________________ with distance

increases

two objects attracting: the PE of the (magnetic/electric/gravitational) field decreases and the speed of the object ________________

increases

two objects repelling: the PE of the (magnetic/electric/gravitational) field decreases and the speed of the objects ________________

electric current

- electric charges in motion

- a battery creates an electric field inside the wires. Negative charges in the wires feel a force due to the electric field and begin moving around the circuit, causing an ______________.

bulb is glowing

when a ________________________, there is evidence of an electric current

magnetic field

when electric charges are moving, they create a _______________________

electric field

when magnetic charges are moving, they create an ________________________