Energy Flashcards
Types of Energy Stores
magnetic
thermal (internal)
chemical
kinetic
electrostatic
elastic potential
gravitational potential
nuclear
Internal energy is the sum of….
the total kinetic and potential energy of the particles in an object.
In hotter objects, the particles have more internal energy and vibrate faster.
Chemical energy is the energy stored in….
the chemical bonds, such as those between molecules.
Methods of Energy Transfer
- HEATING - energy transferred from a hotter object to one with a lower temperature
- WAVES - light, sound, radiation etc.
- ELECTRICITY - electric current
- FORCES - mechanically
how to remember energy stores
kittens go eating together cats not much ever
Explain how energy is transferred when a person stretches a rubber band
When you stretch a rubber band, energy from your chemical store is transferred mechanically to the object’s elastic potential energy store.
Useful vs wasted energy
energy is never transferred completely usefully - some energy is always dissipated.
How to reduce amount of wasted energy?
- lubrication - reduces transfer due to friction.
- streamlining - reduces energy wasted due to air resistance or drag in water.
- thermal insulation - prevents as much energy dissipating into the surroundings
work done aka force x distance can be…
mechanical or electrical
For solids, heat is transferred by…
conduction
For fluids (gas/liquids) heat is transferred by…
convection
For heat to get through a vacuum, heat is transferred by…
radiation (infrared)
Conduction process
- heat makes particle gain kinetic energy and vibrate faster
- due to it vibrating more it collides with neighbouring particles
- they transfer thermal energy to each other - chain reaction
- this continues like a domino effect until the heat spread out evenly
Why does conduction work in solids?
Because the particles are packed tightly together - more collisions possible
When describing a substance’s ability to transfer energy by conduction, we refer to its…
thermal conductivity
Convection process
- particles in fluids are not fixed
- when heated they gain kinetic energy (move faster)
- through the process of random diffusion, the heated particles move to the cooler region
- the heated particles spread out and become less dense
- They float to the (top) and exchange places with the cooler particles which sink to the bottom (of a container)
- this cycle repeats - the heated particles cool down and sink and the cool ones are heated by the heat source and rise due to their less density
The recurring process of convection is called
a convection current
Both convection and conduction work as particles…
gain kinetic energy
However, unlike conduction where the heat is transferred between the particles, in convection…
the particles actually move
Radiation: heat energy can be transferred in a vacuum as they are carried by…
infrared waves
The hotter an object is the more __________ it emmits
radiation
