conservation and dissipation of energy Flashcards
learn science
what is energy transferred between?
energy stores.
name the energy stores (8)
- thermal
- kinetic
- gravitational potential
- elastic potential
- chemical
- magnetic
- electrostatic
- nuclear
how is energy transferred?
mechanically (a force doing work)
electrically (moving charges)
heating
radiation (e.g. light or sound)
what is a system?
a name for an object or group of objects. (such as two colliding cars)
how can energy transfer within a system? (4 ways)
energy can transfer into the system.
energy can transfer out the system.
energy can transfer between objects.
energy can change stores.
what is a closed system?
a system where energy can not enter or leave.
how does energy change in a closed system?
it doesn’t 🤷
what is work done?
work done is another name for energy transferred.
how does work get done?
work is done when current flows or by force moving an object.
what is kinetic energy?
energy stored in a moving object.
when is kinetic energy gained or lost?
kinetic energy is gained when an object speeds up.
kinetic energy is lost when an object slows down.
what is the formula for kinetic energy?
kinetic energy jules = 1/2 x mass kg x velocity² m/s
what is gravitational potential energy?
the energy an object has due to it’s height above the earth’s surface.
why is energy transferred to the gravitation potential store?
lifting an object in a gravitational field requires energy or work which transfers energy to the gravitational store.
what is the formula for gravitation potential energy?
gpe jules = mass kg x gravitational field strength newtons/kg x height m
what happens when an object falls?
energy transfers from its gravitational energy store to its kinetic energy store.
what is elastic potential energy?
energy stored when an object is stretched or squashed.
what is the formula for elastic potential energy?
elastic potential energy jules = 1/2 x spring constant newtons/metre x extension² metres
what is conservation of energy?
energy can be transferred but never created or destroyed.
what is wasted energy in an energy transfer?
the amount of energy transfered to non useful stores.
what is power?
power is the rate of energy transfer. (e.g. a powerful machine transfers a lot of energy in a short amount of time)
what is the formula for power? (2)
power watts = energy transferred jules ÷ time seconds
power watts = work done jules ÷ time seconds
how can you reduce energy dissipation?
lubrication or insulation.
