Hi! Could You Please Help Me See If My Aswers To These Following Physics Q’s Are Correct?
Q1.What type of surface is needed for a petrol container in a hot country?
Rubber as it is a good insulator and will keep all surrounding heat out.
Q2.Why does snow under fallen leaves melt quicker than snow in sunlight.
Because the snow under the leaves are being insulated as the air between snow and leaves warmed to melt snow.
Q3.Are late frosts more likely to occur on cloudy on cloudless nights? Explain answer.
-(what is answer)
Q4.Should surface of kettle be polished or dull black?
Polished.
Q5.Earth been warmed by sun for millions of years so why its temp has remained fairly steady?-(please answer)
Q6.which method of heat transfer are the following appliances designed for:a)electric cooker plate:conduction b)polished backplate of an elctric fire:radiationc)vents at top of solid fuel room heater:(what is it?) c)radiator:convection
Q7.If light surfaces are poor radiators of heat, why are radiators in central heating systems painted white?
-please give answer
5 the earth doesnt just absorb heat only, it also radiate and reflects heat back out
dbl glass prevents convection and some conduction
silvered surface reduces radiation heat transfer
vacuum reduces conduction and convection
Q2.Why does snow under fallen leaves melt quicker than snow in sunlight.
It is not because of insulation (that would produce the opposite affect).
It is because the darker leaves attract sunlight and warm up whereas white snow tends to reflect the light.
Q1 Surface is important, not material, so I would suggest reflective
Q2 The leaf is heated when it absorbs sunlight. Snow is reflects the radiation
Q3 A clear night. Clouds reflect infra red radiation from the earth so heat its surface.
Q4 Dull black would lose heat so polished.
Q5 Most of the heat is reflected
Q6 a,b correct C) vents implies convection, c#2) correct
Q7 They heat by convection not radiation
Q8. a) Convection. b) Conduction c) Radiation
How are heat losses from house reduced?
Loft insulation, Cavity wall insulation, Double glazing, Draft exclusion.
Book answer for 1 is shiny metal or white to reflect sun
please don’t say dark colours attract heat they absorb more radiant heat
3 cloud cover reflects back heat to Earth so cools more slowly
7 to look pretty! they give out heat by convection
1. Wrong! Petrol rots rubber. Try metal.
2. Radiation absorbtion
3. Yes. Clouds hold heat at night.
4. Correct.
5. Because it radiates heat into space at the same rate.
6. Yes, Yes, Yes
7. Because radiator is a misnomer. They mostly work by convection. White looks better.