Energy(p) Flashcards
Is energy created?
No it is not created or destroyed.
But transferred
What are the energy stores?(7!!?)
-thermal (heat)
-kinetic (motion)
-gravitational potential (position of gravity)
-elastic (stretched spring)
-magnetic
-electrostatic
-nuclear ( breaks atom)
-chemical (hold bonds)
How do you transfer energy? (4)
•Mechanically
•heating
•electrically
•radiation
•light
•sound
What is a system???£?
A collection of matter
What is the difference between an open and closed system?(:
Open system: let’s energy be transferred to the outside world( (loses/gain energy via outside)
Closed system: energy not transferred to outside world[ overal zero change]
What is work done (2 things ⚙️⚡️?)
Mechanical: force moved in object
Electrical: current flows energy. Needed to overcome resistance in wire
What is kinetic energy??
Energy it’s posses due to its motion
-more faster mean more kinetic energy
-more mass mean it has not kinetic energy (hence affected by mass and speed)
What is the equation for kinetic energy?
E(small k) = 1/2 mv (squared)
What is Definition of gravity?
A force of attraction between two objects
What is gravitational field?
‘Gravitational field strength’
Has strong forces of attraction
What is gravitational field of earth and moon?
Earth 9.8
Moon 1.6
What is the weight (and equation?)
The force acting in a gravitational field
Mass x gravitational field strength
What is the formula for gravitational potential energy?
E(small p)= mgh
H
What is internal energy?
The total energy stored by the particles making up a substance/system
What is kinetic energy stores?
The movement energy of the particles
(
What happens when you heat up kinetic energy stores?
The internal energy increases. Which then can be used to measure the temperature increase
What is temperature?
Measure of Average internal energy of a substance.
What is specific heat capacity?
The amount of energy needed to raise the temperatures of 1kg of a substance by 1C
What happens to energy when substance cools down?
Substance releases energy
What is the formula which includes change in internal energy, mass, specific heat capacity, temperature change?
Change in internal energy= mass x specific heat capacity x temp. Change
What happens when energy is ‘dissipated’?
It is lost to its surroundings
What is conduction in terms of particles?
Vibrating particles that transfer energy to neighboring particles. (Occurs in a solid)
so lots of collisions happen
What is thermal conductivity?
How well objects transfer energy by conduction
(Metals have high TC, plastic and fluids have low TC)
What is convection m?
Where particles move to gain kinetic energy
What is raidiation?
heat energy transferred without particles, carried by infrared waves
[The hotter the objects, the more radiation!]
What is a fluid?
A substance in which particles are free to move around- include liquid and gas
What is a convection?
When heat is transferred through liquids and gassed
What is conduction?
When heat is lost directly through a solid
What are the two method to reduce unwanted energy transfers?
-thermal institution
-lubrication
How are homes insulated to keep heat?
• have foam seals
• walls
• window
•thick walls
•cavity walls
•double glazing windows
What are cavity walls?
2 walls which have insulating foam between them. Which has pockets of air. As air is a good heat insulator
What are double glazing windows?
Two glass layers that have an air gap in between. To reduce not only convection, but conduction
Why do we reduce friction to reduce unwanted energy transfers?
As friction reduces the EFFICIENCY of energy transfer
What methods are there to reduce friction?
-oil added on cogs to make it easier to peddle
-vehicles are streamlined to reduce friction from air resistance. Allowing less fuel to be used
What is power?
The rate at which energy is transferred/ work is done
P=E/T
P=W/T
What is work done?
When force is used to move object by certain distance
Does energy transfer need force?
No, it does not need force or movement
What are the measurement for power,energy/work done and time?
Power is watts
Energy is Joules
Time is seconds
What is efficiency?
Proportion of energy supplied to the useful energy output
What is the equation for efficiency?
Efficiency = useful energy output/ total energy input
Or
Efficiency = useful power input/ total power input
Can be calculated to either: decimal or percentage
What are renewable resources?
Infinite resources.
-solar
-wind
-Hydroelectric
-tidal
-geothermal
-biofuel
What are non-renewable resources?
Finite resources
-natural gasses
-coal
-oil
-nuclear
What is energy used for? In life
Transport: cars, Planes and trains (Cole, electricity and biofuel)
Domestic: cooking and heating ( coal, natural gas, solar and biofuels)
what are fossil fuels
hydrocarbons from remains of dead plants and animals
3 examples of hydrocarbons
coal, crude oil, natural gas
when fossil fuels are burnt, what do they provide?
-energy used for direct use, (cooking
-power for engines
-generate electricity
what are pros of fossil fuels for energy?
cheap
can be used in any condition
there is lots of infrastructure designed to run on fossil fuels
what are cons of using fossil fuels for energy?
is a limited resource
produces carbon dioxide when burned
sometimes produce toxic gases when burned
what is nuclear energy?
energy obtained by nuclear reactions (nuclear fusion reaction)
what does nuclear energy provide?
electricity that can be transmitted to homes and factories
what are the pros of using nuclear energy?
doesn’t release pollutants, can be used in any condition, it is very unlikely to run out
what are the cons of using nuclear energy?
it is a finites resource, produces radioactive waste that harms organisms, expensive, and there is a small chance of a nuclear meltdown=more waste
how do you produce wind energy?
via turbines, which are placed in strong winds, so the wind can spin the blades, producing kinetic energy, moving the generator, that then produces electrical energy for national grid
how do you produce solar energy?
using solar cells, which generate electrical currents directly from sunlight, which is useful in remote regions
what are the pros of wind and solar energy?
-has low running costs
-doesn’t produce pollutants
-is environmentally friendly
what are the cons of wind and solar energy?
-has high production cost=pollution via production
-dependent on weather
-requires large areas, as there needs to be lots of wind turbines and solar cells to produce large amounts of energy
What are the two hydroelectricity machinery and what do they do?
-Hydroelectric dams: trap water that comes from upstream, into reservoir, making dam full of water
-tidal barrages: making use of tides so water is trapped on one side of dam(one get high)
These are due to Effectc of moon gravity on tides ,cause rise=high tides and fall=low tides
How does hydroelectric produce electricity?
-different water levels cause huge amount of gravitational potential energy to be turned into electricity
-the from water levels changing. Turbines spin in the dam producing kinetic energy converted to motor into electrical energy
What are pros and cons and hydroelectricity?
Pros:
-low running cost
-reliable source
-no pollution
-renewable
Cons:
-big impact on environment
-initial purchase is expensive
What is momentum?
Mass x velocity
What does the conservation of mass state?
States that in a closed system the total momentum before=total momentum after event
-also after collision particle is treated as a single large particle
How much momentum do objects have
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