physics P1

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  • Created by: jl45
  • Created on: 29-03-16 13:36
Describe the three ways that heat energy can be transferred
radiation: All objects are continually emitting and absorbing infrared radiation. Infrared radiation is emitted from the surface of an object. conduction: conduction of heat energy is the process where vibrating particles pass on their extra kinetic
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Describe the three ways that heat energy can be transferred (2)
energy to neighbouring particles. Convection: This occurs when the more energetic particles move from the hotter region to the cooler region- And take their heat energy with them.
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true or false? An object thats cooler than its surroundings emits more radiation than it absorbs
false. An object thats hotter than its surroundings absorbs more radiation than it absorbs (as it cools down). And an object thats cooler than its surroundings absorbs more radiation than it emits ( as it warms up)
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Explain why solar hot water have a matt black surface.
Dark matt surfaces absorb infrared radiation falling on them much better than light, shiny surfaces such as gloss white or silver.
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Describe the arrangement and movement of the particles in a solid
strong forces of attraction to hold the particles close together in a fixed, regular arrangement. The particles don't have much energy so they can only vibrate about their fixed positions.
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describe the arrangement and movement of the particles in a liquid
There are weaker forces of attraction between the particles. The particles are close together, but can move past each other, and form irregular arrangements. They have more energy than the particles in a solid - they move in random directions.
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describe the arrangement and movement of the particles in a gas.
They are almost no forces of attraction between the particles. The particles have more energy than those in liquids and solids- they are free to move, and travel in random directions and at high speeds.
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Which type of heat transfer cant take place in solids? conduction or convection?
convection
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Describe how the heat from heater coils is transferred throughout the water in a kettle. What is this process called?
Heat is transferred from the heater coils to the water by conduction (particle collisions) The particles near the coils get more energy so they start moving around faster. This means theres more distance between them, ie. the water expands and become
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Describe how the heat from heater coils is transferred throughout the water in a kettle. What is this process called? (2)
less dense. This reduction in density means that the hotter water tends to rise above the denser, cooler water. As the hot water rises it displaces (moves) the colder water out of the way, making it sink towards the heater coils- convection currents.
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How do the densities of liquids and gasses change as you heat them up.
They become less dense.
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What happens to the particles of a gas as it turns into a liquid?
When a gas cools, the particles in the gas slow down and lose kinetic energy. The attractive forces between the particles pull them closer together. If the temperature gets cold enough and the gas particles get clos enough together then condensation
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What is the name given to the process where a gas turns to a liquid?
condensation
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Why does evaporation have a cooling effect on a liquid?
The fastest particles with the most kinetic energy are most likely to evaporate from the liquid- so when they do, the average speed and kinetic energy of the remaining particles decreases. This decrease in average particle energy means the tempreture
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Why does evaporation have a cooling effect on a liquid? (2)
of the remaining liquid falls- the liquid falls.
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how does the surface area affect the rate of heat energy?
The bigger the surface area, the more infrared waves that can be emitted from ( or absorbed by) the surface- so the quicker the transfer of heat.
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Describe two features of a vacuum flask that makes it good at keeping hot liquids hot.
1) The glass bottle is double-walled with a vacuum between the two walls. This stops all conduction and convection and conduction through the sides. 2) The walls either side of the vacuum are silvered to keep heat loss by radiation to a minimum.
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Do animals that live in hot climates tend to have large or small ears?
larger ears with a larger surface area to allow them to lose heat by radiation easily and keep cool.
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If it costs £4000 to double glaze your house and the double glazing saves you £100 on energy bills every year , calculate the payback time for double glazing.
4000/100 = 40 years
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Name 5 ways of improving energy efficiency in the home.
1) loft insulation 2) hot water tank jacket 3) cavity wall insulation 4) double glazing 5) draught-proofing
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explain how cavity wall insulation reduces heat loss.
Foam is squirted into the gap between the bricks reduces convection and radiation across the gap. Pockets of air in the foam reduce heat transfer by conduction.
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explain how loft insulation reduces heat loss
A thick layer of fibreglass wool laid out across the whole loft floor reduces conduction and radiation into the roof space from the ceiling.
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Explain how draught- proofing reduces heat loss
Strips of foam and plastic around doors and windows stop draughts of cold air blowing in ie. they reduce heat loss by convection.
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Explain how hot water tank jackets and thick curtains reduce heat loss.
hot water tank jackets- lagging such as fibreglass wool reduces conduction and radiation. Thick curtains- big bits of cloth over the window to reduce heat loss by conduction and radiation.
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what can you tell from a materials U-value
U-values show how fast heat can transfer through a material.
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Would you expect copper or cotton wool to have a higher u value
cotton wool because copper is a metal. Metals are good conductors of heat so u-value would be lower than cotton wool.
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What property of a material tells you how much energy it can store?
The specific heat capacity of a material tells you how much energy it can store.
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An ornament has a mass of 0.5 kg. The ornament is made from a material that has a specific heat capacity of £1000 J/kg. How much energy does it take to heat the ornament from 20 to 200 degrees.
Energy transferred= mass X specific heat capacity X temperature change so 0.5 X 1000 X 180 = 90,000 joules.
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Do heaters use materials that have a high or low heat capacity.
Materials used in heaters usually have a high specific heat capacity so that they can store large amounts of heat energy.
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Name 9 types of energy and give an example of each
1) Electrical energy eg. current flows 2) light energy ( sun, light bulbs) 3) sound energy ( loudspeakers) 4) kinetic energy ( anything moving) 5) nuclear energy ( nuclear reactions) 6) thermal energy or heat ( flows from hot objects to colder ones.)
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Name 9 types of energy and give an example of each (2)
7) gravitational potential energy ( anything that can fall) 8) elastic potential energy ( stretched springs, elastic, rubber bands) 9) chemical energy eg. foods, fuels ect.
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State the principle of the conservation of energy.
Energy can be transferred usefully from one form to another, stored or dissipated- but it can never be created or destroyed.
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List the energy transformations that occur in a battery- powered toy car
chemical energy------- heat and electrical energy
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What is the useful type of energy delivered by a motor? in what form is energy wasted?
kinetic energy and wasted is heat and sound energy.
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What is the efficiency of a motor that converts 100J of electrical energy into 70J of useful kinetic energy?
70/100 = 0.7 J
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what are the standard units of electrical energy?
kilowatts.
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Calculate how many KWh of electrical energy are used by a 0.5 Kw heater used for 15 minutes.
energy= power X time so 0.5 X 15 = 7.5 KWH
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Would a battery-powered radio or a clockwork radio be more suitable when camping? why?
battery powered because it will last and function without energy.
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what is meant by non-renewable energy sources?
they will run out one day, they all do damage to the environment and they provide most of our energy.
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name 4 different non-renewable energy sources
1) coal 2) oil 3) natural gas 4) nuclear fuels (uranium and plutonium)
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Explain how electricity is generated in a gas-fired power station . Describe the useful energy transfer that occurs
The fossil fuels are burned to convert its stored chemical energy into heat (thermal) energy. The heat energy is used to heat water ( or air in some fossil fuel power stations to produce steam. The steam turns a turbine, converting heat energy into
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Explain how electricity is generated in a gas-fired power station . Describe the useful energy transfer that occurs (2)
kinetic energy. The turbine is connected to a generator which transfers kinetic energy into electrical energy.
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Describe how the following renewable resources are used to generate electricity. State one advantage and one disadvantage for wind power.
Wind power involves putting lots of windmills up in exposed places. Each wind turbine has its own generator inside it. The electricity is generated directly from the wind turning the blades, which turn the generator. An advantage is that theres no
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Describe how the following renewable resources are used to generate electricity. State one advantage and one disadvantage for wind power. (2)
pollution but it spoils the view and is very noisy.
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Describe how the following renewable resources are used to generate electricity. State one advantage and one disadvantage of solar cells.
Solar cells generate electric currents directly from sunlight. Solar cells are often the best source of energy for calculators and watches. There is no pollution but expensive.
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Describe how the following renewable resources are used to generate electricity. State one advantage and one disadvantage of tidal power.
The movement of tides drives turbines. A tidal barrage (a kind of dam) is built across estuaries, forcing water through gaps.Potential to generate a lot of energy but construction of barrage is very costly.
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Describe how the following renewable resources are used to generate electricity. State one advantage and one disadvantage of wave power.
The movement of seawater in and out of a cavity on the shore compresses trapped air, driving a turbine.Ideal for an island country. Construction can be costly
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Describe how the following renewable resources are used to generate electricity. State one advantage and one disadvantage of geothermal energy.
In volcanic regions it is possible to use the natural heat of the earth. Cold water is pumped under ground and comes out as steam. Steam can be used for heating or to power turbines creating electricity.
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Describe how the following renewable resources are used to generate electricity. State one advantage and one disadvantage of geothermal energy (2)
Potentially infinite energy supply butCan be expensive to set up and only works in areas of volcanic activity.
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Why are hydroelectric power stations often located in remote valleys?
because energy is harnessed from the movement of water through rivers, lakes and dams.
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What is the purpose of pumped storage?
hydroelectric power station water is stored behind a dam in a reservoir. This water has gravitational potential energy. the water runs down pipes (potential to kinetic energy) to turn the turbine the turbine is connected to a generator to produce
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What is the purpose of pumped storage? (2)
electricity (kinetic to electrical energy)
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why is wave power only a realistic major energy source on small islands?
Ideal for an island country, because not all places have sea water and
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What is the source of energy for tidal barrages?
tidal power.
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Apart from generating electricity, how else can geothermal heat be used
geothermal heat is used to heat buildings directly, without being converted to electrical energy.
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How are biofuels produced? give two examples of biofuels.
Biofuels are renewable energy resources. They're used to generate electricity in exactly the same way as fossil fuels- they're burnt to heat up water eg. ethanol and methane.
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Name two places that carbon dioxide can be stored after carbon capture.
1)involves separating carbon dioxide from waste gases. The carbon dioxide is then stored underground, for example in old oil fields or gas fields such as those found under the North Sea. 2) storing carbon dioxide dissolved in sea water (bottom of sea
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Name six factors that should be considered when a new power station is being planned.
1) set-up costs 2) reliability issues 3) environmental issues 4) set up/ decommissioning time 5) running fuel/costs 6) location issues
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Which three energy sources are linked most strongly with habitat disruption?
hydroelectric, tidal, biofuels.
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Explain why a very high electric voltage is used to transmit electricity in the national grid?
to reduce energy losses during transmission. Transformers are used to increase or decrease the voltage of the supply.
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Find the speed of a wave with a frequency 50 KHz and a wavelength 0.3 cm.
speed= frequency X wavelength so 50 X 0.3 = 15 M/s
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Why does light bend as it moves between air and water?
Light waves change speed when they pass across the boundary between two substances with a different density, such as air and glass. This causes them to change direction, an effect called refraction.
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what is diffraction?
When waves meet a gap in a barrier, they carry on through the gap. However, the waves spread out to some extent into the area beyond the gap. This is diffraction.
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what size should the gap be in order to to maximise diffraction?
A gap similar to the wavelength causes a lot of spreading with no sharp shadow eg sound through a doorway.
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Put the EM spectrum in order from longest wavelength and lowest frequency.
radio waves (television signals) ,microwaves (cooking, mobile phones), infrared (optical fibre communication) , visible light (seeing) ,ultraviolet (detecting forged bank notes) , X-rays( medical images of bones) ,gamma rays killing cancer cells.
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Describe the main known dangers of microwaves, infrared, visible light, UV and x-rays.
damaging cells.
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why cant sound waves travel in space?
sound cant travel in space, because its mostly a vacuum ( there are no particles).
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describe a transverse wave
In transverse waves the vibrations are perpendicular at 90 degrees to the direction of energy transfer of the wave.
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describe a longitudinal wave
in longitudinal waves the vibrations are parallel to the direction of energy transfer of the wave.
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Are high frequency sound waves high pitched or low pitched?
high pitched.
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If a wave source is moving towards you, will the observed frequency of its waves be higher or lower than their actual frequency?
lower then their actual frequency
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what do red-shift observations tell us about the universe?
all the galaxies are moving away from us so the universe is expanding
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describe the big bang theory
The theory states that originally all the matter in the universe was concentrated into a single incredibly tiny point. This began to enlarge rapidly in a hot explosion (called the Big Bang), and it is still expanding today.
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What evidence is there for the big bang theory?
Red shift,Cosmic Microwave Background radiation (The relatively uniform background radiation is the remains of energy created just after the Big Bang.)
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describe red shift
When we look at the spectrum of a distant star, the absorption spectrum is there, but the pattern of lines has moved towards the red end of the spectrum.
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Other cards in this set

Card 2

Front

Describe the three ways that heat energy can be transferred (2)

Back

energy to neighbouring particles. Convection: This occurs when the more energetic particles move from the hotter region to the cooler region- And take their heat energy with them.

Card 3

Front

true or false? An object thats cooler than its surroundings emits more radiation than it absorbs

Back

Preview of the front of card 3

Card 4

Front

Explain why solar hot water have a matt black surface.

Back

Preview of the front of card 4

Card 5

Front

Describe the arrangement and movement of the particles in a solid

Back

Preview of the front of card 5
View more cards

Comments

Elham Ishaque

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Very useful. Thank you!

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