Physics T1 Flashcards
Energy
How many energy stores are there?
eight.
What are the eight energy stores?
-Kinaesthetic
-gravitational
-chemical
-nuclear
-thermal
-magnetic
-electrostatic
-elastic potential
what is a closed system?
A system where neither matter nor energy can enter or leave.
What are the four main energy transfers (& examples)
-mechanically; object moving due to force (pushing/pulling)
-electrically; current moving through PD (charge moving round a circuit)
-heating; energy transfer from cold to hotter object (pan heating water on a hob)
-radiation; energy transferred by light/sound waves (light energy from sun reaching earth)
What is work done?
energy transferred.
What is the conservation of energy principle?
Energy can be transferred usefully, stored, or dissipated but never be created or destroyed.
What has a kinetic energy store?
Anything that moves.
When is energy transferred to the GPE store?
If the object is lifted.
What is the gravitational field strength on earth roughly?
9.8 N/kg
what happens when energy is lost from the g.p.e store?
Energy is gained in the kinetic energy store.
What can transfer energy to an objects elastic potential energy store?
stretching or squashing an object.
what is specific heat capacity?
The amount of energy needed to raise the temperature of a 1kg substance by 1 degree C
briefly explain the steps in the investigating specific heat capacity practical.
- measure mass of block then wrap in insulation (reduce energy transfers)
- measure initial temp of block and set PD to 10V
- Turn on power supply and take readings (temp and current every 10 mins) as block heats up.4
briefly explain the steps in the investigating specific heat capacity practical.
- measure mass of block then wrap in insulation (reduce energy transfers)
- measure initial temp of block and set PD to 10V
- Turn on power supply and take readings (temp and current every 10 mins) as block heats up.
what conclusion can be drawn from the specific heat capacity experiment?
When power is on the current does work on the heater, transferring energy electrically from the power supply to the heaters thermal store. This energy is then transferred to the materials thermal store by heating, causing the materials temperature to increase.
summarise equipment needed in the specific heat capacity practical.
-thermometer
-heater
-insulation
-ammeter
-power supply
-block of material.
what is power?
Power is the rate of energy transfer.
what is power measured in?
Watts (W)
what are the two equations for power?
Power= energy/time
power= work done/time
what is conduction?
Conduction is the process by which vibrating particles transfer energy to neighbouring particles.
which state of matter does conduction occur the most in?
Conduction occurs the most in solids.
what is convection?
Convection is where energetic particles move away from hotter regions to cooler regions.
In which state of matter can convection occur?
Convection can occur in liquids or gases.
Finish the sentence
The higher a materials thermal conductivity…
… the faster energy can be transferred through it by conduction.
What is thermal conductivity?
The thermal conductivity of a material is a measure of its ability to a particular material conduct heat.
What are three types of thermal insulators in homes?
-loft insulation
-double glazing
-cavity wall insulation.
What is insulation used for?
It is used for reducing unwanted energy transfers.
what are lubricants used for?
Lubricants are used to reduce friction between object’s surfaces when they move.
what are the two equations for efficiency?
efficiency= useful output energy transfer/total input energy transfer.
efficency= useful power output/total power output.
which store is most wasted energy transferred to?
The thermal store.
Give 4 non renewable energy sources.
-coal
-oil
-gas
-nucleur fuels
Give 4 renewable energy sources.
-Wind
- Tides
- solar power
-hydroelectricity
what are two uses of energy sources
-tranport
-heating
give two problems about renewable energy sources.
-They often don’t provide as much energy as non-
renewable sources.
-Some depend on the weather making them unreliabke.
How is geothermal power generated?
It uses the thermal energy stores of hot underground rocks to generate electricity.
How is wind power generated?
The blades are turned by the wind which turns the generator.
How is solar power generated?
The solar cells generate electric current directly from the suns radiation.
How is hydroelectric power generated?
Usually requires the flooding of a valley by building a dam.
Water is held back by the dam and then when it is released it passes through turbines which turns a generator- generating electricity.
What is a problem with the way hydroelectric power is generated?
Big impact on envirnment- flooding of valley means rotting vegetation (releasing methane and CO2) and also causing habitat loss.
How is wave power generated?
Waves force air through the turbine, turning a generator generating electricity.
How are tides produced?
by the gravitational pull of the sun and the moon.
What are tidal barrages?
They are big dams built across river estuaries.
How do tidal barrages generate electricity?
The water is held back behind the barrage then allowed to flow through turbines connected to generators, generating electricity.
What are bio fuels?
Bio fuels are renewable energy resources created from either plant products or animal dung.
How do bio fuels produce electricity?
They can be burnt in the same way as fossil fuels.
Give an advantage of using bio fuels.
They are fairly reliable as the crops take a short time to grow and can be grown all year round.
Give a disadvantage of using biofuels.
They release CO2 and methane into the atmosphere because the plants originally absorb it meaning when they get burnt it is released again.
Give three examples for using fossil fuels.
-reliable
-cost effective
-enough to meet demand.
why is nuclear power ‘clean’
It doesn’t release any harmful gases or other chemicals into the atmosphere.
what are two disadvantages of using nuclear fuels.
-high cost
-difficult to dispose of.
Why has the energy usage in the UK been decreasing slightly since the start of the 21st centuary?
Because appliances have become more efficent.
What happens to a substance if it is heated and changes directly from a solid to a gas?
It sublimates
what is ionisation?
Ionisation is the addition or removal of an electron to create an ion
what is condensation?
the process where water vapour becomes liquid.
what is an advantage of transmitting electricity at a very high PD?
Less thermal energy is transferred into surroundings.
equation for charge flow?
charge flow= power/ potential difference
whats the equation for power?
power= potential difference x current
What are two advantages of taking multiple measurements and calculating a mean value?
- identifies anomalous results so they can be ignored.
- reduces effect of random effect of random errors when using equipment.
equation for density?
density = mass/ volume
what are the three types of error?
systematic
zero
random
What is the same for all atoms of the same element?
atomic number.
what is different for isotopes of the same element?
number of neutrons.
what is meant b y half life?
The rime it takes for the count rate of a radioactive sample to halve.
What happens to energy that is dissapated?
It becomes less useful
what is the equation for kinetic energy?
Ek= 1/2 (mv)2
What is the equation for energy transferred?
energy transferred= power x time
what is nuclear fission?
the joining together of nuclei
What happens during nuclear fission
total mass of particles decreases.
What are two environmental impacts of burning fossil fuels?
- releases CO2 causing global warming
- releases sulphur dioxide causing acid rain.
What is electric current?
charge
what colour is the live wire?
blue.
what colour is the earth wire?
green and yellow
What colour is the neutral wire?
brown
What is the purpose of the earth wire?
Connects appliance to the earth, preventing it from becoming live if theres a fault.
What is the frequency and potential difference of the mains electricity supply?
PD: 230 V
frequency: 50 Hz
what are thermistors dependant on?
Heat.
What are LDRs dependant on?
Light intensity.
What are thermistors used for?
thermostats
What are LDRs used for?
switching on lights when its dark.
what does the live wire do? (blue)
carries alternating current.
What is the national grid?
System of cables and transformers linking power stations to consumers.
What is the function of a step up transformer?
decreases current by increasing PD. Because if theres high current and wires get hot energy is wasted.
What is the function of a step down transformer?
decreases PD to 230 V so it is safer for domestic use.
What happens when insulating materials are rubbed together?
They become electrically charged; negatively charged electrons are rubbed off and transferred from one material to another.
In which state of matter is compression possible?
Gas
What happens when substances change state?
Mass is conserved.
How do you calculate volume of a regular shape?
width x height x length
How do you calculate the volume of an object?
-fill up can with measured volume of water
-submerge object in water
-measure water displaced
What is internal energy?
Energy stored inside a system by the particles that make up a system.
What two things happen when a system is heated?
- temperature change
- changes state
