gcse physics topic 1

energy and energy throughout the home and sources.

what is a system

an object or group of objects

what is a system in equilibrium

nothing changes in a system

what is energy measured in

joules

what is kinetic energy

moving objects have energy in this store

what is gravitational potential

objects gain energy ini this store when they are lifted through a gravitational field

what is elastic energy

objects gain this energy when they are stretched or compressed.

what is magetic energy

magnetic materials interacting with each other have this energy

what is electrostatic energy

objects with a charge interacting have this energy

what is nuclear energy

atomic nuclei release energ from their nuclear store during nuclear reactions

what is thermal energy

all objects have this. the hotter it is the higher the energy in the store.

what are the 4 ways energy can be transferred

mechanicaly, electrically, heating,radiation

what is mechanical transfer

when force acts on object

what is electrical transfer

when a charge moves through a pd

heating(particles)

energy is transferred from hotter to colder(conduction)

radiation

em waves

explain the changes in energy stores when person holds then throws ball.

the person has energy in their chamical store. the ball is thrown increasing its kinetic energy while decreasing the chemical energy store. as the height increases kinetic store traansferrs to gravitational potential energy store. when it falls it goes back to kinetic. when it hits the floor the kinetic is transferred to elastic energy.

formula for kinetic energy:

½ x m(kg) x v(m/s)^²

formula for gpe:

mass(kg) x g(n/kg) x h(m)

formula for elastic potenital energy:

½ x k(n/m) x e²(m)

formula for change in energy:

mass x shc(j/kg c) x temp change

what is the specific heat capacity

amount of energy needed to raise the temperature of 1kg oof substance by 1 degree celcius.

what would a high shc mean

it takes more energy to change its temperature

do good thermal conductors have high or low shc

low

what is power

the rate of energy transfer from one store to another is called power, two cars can accelerate to the same final speec but the one with the most power will reach that speed sooner.

what is the formula for power

power = energy(watts)/time(seconds)

what is the law of conservation of energy

energy cannot be created or destroyed, just transferred from one store to another.

what does it mean when energy is dissipated to the surroundings

when energy transfers are not useful

when light is produced what is the wasted energy’s store

thermal because visible light is em radiation so energy is transferred by radiation

when sound is produced what is the wasted energy’s store

thermal becuasound waves make air particles vibrate increasing thermal. energy store of the air.

what is thermal conduction

when energy us transferred by vibrating particles and the vibrating particles transfer energy from their kinetic stoore to the kinetic store of neighbouring particles.

what are insulators

a substance that is a poor thermal conductor

what is insulation made of and why

it is made of fibreglass since air is trapped between the fibreas making it a good insulator

what parts of a house are insulated

the loft of a house. filled cavity in walls. double glazed windows

why are windows double glazed

Double glazing adds a second layer of glass to a window, either as a sealed unit or secondary glazing. Both create a small air gap between panes.

In sealed units, the gap is sealed at low pressure (not a vacuum) and contains dried air to prevent misting. Secondary glazing involves an inner frame with an openable pane, but some condensation may occur.

The trapped air acts as an insulator, slowing conduction and, due to the narrow gap, reducing convection. This keeps rooms warmer for longer and lowers heating costs.

Radiation still passes through, with minimal reflection and increased absorption by glass, but overall radiation transfer is barely affected.

what is efficiency

measure of the amount of wasted energy in an energy transfer

formula for efficiency:

useful output/total input

how can efficiency be improved in a machine

lubrication or thermal insulation

describe how hydro electric dam works

gpe store of water is transferred to kinetic energy of the turbine mechanically.

describe how fuels produce electricity.

fuels (chemical) heat water creating steam (kinetic energy) turning a turbine with sends power awa through the grid.

how does geothermal energy produce electricity

water is pumped down to hot rocks and returns as steam

name energy resources(9)

fossil fuels, nuclear, bio fuels, wind, hydroelectric, tidal, geothermal, solar, water waves