Physics- P1.1

Frage	Antworten
What happens when an object absorbs any type of electromagnetic radiation?	It gets hotter
Which type of radiation gives the most effect?	infra-red
Explain how a person sitting next to a fire gets hot?	The energy from the fire is transferred through the air by electromagnetic waves The person in front of the fire feels warm because they absorb some of this energy
When do objects increase in temperature?	When they absorb infra-red radiation faster than they emit it
The hotter the object...	The more infra-red radiation radiates each second
Put 4 surfaces in order of best to worst reflectors	shiny white matt white shiny black matt black
Put the same 4 surfaces in order if best to worst emitter and absorber?	matt black shiny black matt white shiny white
What 2 word describe an experiment that repeats and always gets the same results?	repeatable and reproducible
What could an error in reading the thermometer give?	an anomalous result
What are the three states of matter?	solid, liquid and gas
What does kinetic theory state?	All matter is made up of small particles that are constantly moving- the higher the temperature the higher the particles move
When do particles attract each other strongly?	When they are close together
Describe the 2 facts particles in a solid? What happens when a solid is heated?	Particles are packed close together in a fixed pattern. Particles are constantly vibrating but kept in position by strong attractive forces. The particles vibrate faster and take up more space- so the solid has expanded a little
Describe 3 facts about the particles in a liquid? When does a liquid turn into a gas?	Particles are close together- but the forces aren't strong enough to hold them in a fixed pattern. They are able to move and slide about This means a liquid can flow and change shape to fit any container When particles at the surface have enough energy to break away
Describe the 2 facts about particles in a gas?	Particles are a long way apart with virtually no forces between them- so a gas is easy to compress The particles have a rapid, random motion and quickly fill any space available to them
What is evaporation?	When a liquid changes into a gas without boiling
How can kinetic theory explain evaporations?	The particles in a liquid have a range of speeds If one of the faster moving particles is close to the liquid surface it might have enough kinetic energy to break away and escape from the liquid
4 ways a liquid can be made to evaporate faster? Explain?	Increasing the temperature-increases the speed of particles so more will have enough energy to escape Increasing surface area-lets more of the faster particles be next to the surface so particles escape at a faster rate Having a draught of wind-moves many of the escaping particles away from the surface before thy fall back in Reducing the humidity- reduces the amount of water vapour in the air, reducing the number of particles from the water vapour falling back into the liquid
After evaporation, why is the average energy of the particles less than before?	Because when a liquid evaporates it looses it's fastest particle-the ones with the most energy
What also lowers when the lower average energy is lower?	The temperature
What is condensation? How does it happen?	When a gas changes back into a liquid When warm damp air hits a cold surface, it cools and some of the water vapour in the air changes back into a liquid
!!!!!!!Explain the process of conduction Is it a fast or slow process?	At the hot end of the conductor, energy is transferred to the atoms increasing their kinetic energy The atoms vibrate faster and with a bigger amplitude These atoms collide with neighbouring atoms The extra kinetic energy is passed on from atom to atom slow
Explain why metals are better conductors than non-metals?	Metals have electrons that are free to move These free electrons transfer energy rapidly whereas non-metals have no free electrons so conduct energy slowly
What is a poor conductor good at?	Insulating
Explain how air helps a polar bear keep warm?	Their thick fur traps small pockets of air Air reduces the energy of transfer by conduction, helping the polar bear keep warm
What does states of matter does convection happen in?	liquids and gases
Definition of convection?	The transfer of thermal energy by the movement of a liquid or gas due differences in density
Describe the process of convection in air	Air particles gain energy and move around more quickly The particles move apart taking up more space The war air expands becoming less dense than the colder air around it The war air rises, pushing colder denser air downwards
!!!!!!!!!What 4 things does does the rate or transfer of energy depend on?	The material the object is made from The surface area and volume of object The surface the object rests on The difference in temperature between the object ad it's surroundings
3 ways a vacuum flask helps to keep drinks warm	The vacuum between the double glass walls-stops convection and conduction The silvering on the glass walls-radiation Plastic stopper- stops conduction and radiation
!!!!!What do most methods of insulation involve? 2 reasons why?	Trapping air because air trapped in small air pockets cant move far - so energy transferred by convection is reduced Air is a good insulator - energy transferred by conduction is reduced
How do double glazed widows help insulate houses?	They two sheets of glass with air and argon in-between them the air and argon is a good insulator-reducing air loss by conduction The gap between the sheets is thin-reducing air loss by convection
What do u-value measure?	How good an insulator a material is
The lower the u-value... The higher the u-value...	the better the insulator the faster the material will transfer thermal energy
what is the equation for finding out it's specific heat capacity?	e = m x c x 0 special o 0

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