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Physics

Greta Agnew Inglés 25 fichas

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1Suggest why Design A is better than Design BWater stays in the solar heater for longer
so the water gets warmer
2—Reflect the heat or infrared back to the pipe
to make the water warmer.
3Which types of surfaces absorb more heat radiation? Which types absorb less?Good absorbers-Dark, matt, dull surfaces
Poor absorbers- Light, shiny surfaces
4What is the arrangement of solid, liquid, and gas particles?Solid- Close together, regular pattern
Liquid- close together random
Gas- far apart, random
5What is conduction?The movement of something such as heat or electricity through a solid or passage
6—Ions or electrons or particles gain (kinetic) energy.
More vibration of ions or vibration with bigger amplitude.
Energy is transferred by collisions between vibrating ions/electrons/particles.
7—No free electrons or atoms/molecules/particles
Not arranged in neat rows.
8—Temperature gets higher than steel.
Temperature gets higher quicker or copper heats up quicker.
Heat is conducted or spread more evenly (than steel).
9What is convection?Convection occurs when particles with a lot of heat energy in a liquid or gas move and take the place of particles with less heat energy. Heat energy is transferred from hot places to cooler places by convection.
10—Air particles / molecules / atoms at the bottom gain energy.
Air particles / molecules / atoms move faster.
Particles / molecules / atoms move apart.
Air expands.
Air becomes less dense.
Warm / hot air rises.
11What is evaporation and condensation?Condensation is the change from a vapor to a condensed state (solid or liquid). Evaporation is the change of a liquid to a gas.
12https://www.goconqr.com/en-US/p/4262730There are attractive forces between molecules or particles in the tea.
Only the fastest molecules/particles have enough energy to break away from others.
These molecules or particles escape from the surface of the tea.
So the average speed or energy of the remaining molecules or particles goes down.
Lower average speed or energy of molecules means lower temperature of the tea.
13—Larger temperature difference
between the tea and the air.
14What factors affect heat loss?Outside and inside tempretures
Size
Shape
Construction of the material
15—
16What is a U-value?A U-value measurs the effiency of something that is used to reduce heat energy transfer
17—Air is a good insulator or air is a poor conductor.
(because) The particles are far apart.
Convection is prevented or no convection.
18Why is water a good substance to have in a HOT water bottle?Large amount of energy needed
to raise the temperature (by 1 degree)
Large amount of heat energy released
for each degree
19Calculate the efficiency192/200=96% or 0.96
20—LED is more efficient.
LED is 80% efficient.
Less energy wasted or transferred as heat.
Four times more energy transferred as useful / light by LED.
Tordio needs to be wound less for LED.
21—The total energy in is the same or equal to the total energy out (or it is the same).
22—Sound energy- 20 J
Heat energy- 30 J
23Explain the role of transformers in the National Grid. (4 points)Transformers (or step up transformers) can reduce the current through the cables
or increases p.d. (or potential difference) across the cables.
Which reduces the energy loss from the cables.
Which increases the efficiency (of the National Grid).
Transformers also reduce the p.d. to a safe level for consumers.
24Describe the process by which electricity is generated using fossil fuels. Include any energy transfers involved in your answer.Coal, oil, or gas is burned in a boiler, the heat produces steam which turns a turbine to generate electricity to power homes
25What is the difference between transverse and longitudinal wavesTransverse- Perpendicular to the direction of the wave.
Longitudinal- Parralel to the direction of the wave.