Heat, energy and energy transfer Flashcards

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1
Q

define heat

A

a form of energy measured in joules

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2
Q

difference between heat and temperature

A

adding heat will cause temperature to rise

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3
Q

3 effects of adding and removing heat energy

A

increases temperature
causes expansion of material vs contraction
changes state of a substance (solid-liquid-gas)

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4
Q

show that solids expand when heat energy is added

A

a metal ball on a skewer, a ring with the same diameter as the metal ball. Heat the metal ball over the bunsen burner, it won’t fit through the ring. Cool it down in water, it will fit.

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5
Q

show that liquids expand when heat energy is added

how is this principle used in life

A

a beaker with water on a stand over a bunsen burner. a conical flask inside the beaker with alcohol, and a glass tube coming up from the conical flask. As the water heats, the level of alcohol in the glass tube will rise because it has expanded.
thermometers with alcohol or mercury use this

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6
Q

how is water different

A

it expands when it freezes - makes water pipes burst

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7
Q

show that gases expand when heated and contract when cooled

A

beaker with water on bottom. Conical flask upside down above beaker, with glass tube coming out of it into the water. heat the conical flask from the outside with a bunsen burner- bubbles should be seen. As it cools down, the glass tube will suck up water because the air inside is contracting.

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8
Q

what are the 3 ways heat energy moves from a warm place to a cool place?

A

conduction, convection, radiation

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9
Q

define conduction

A

the movement of heat energy through a substance without any overall movement of the substance itself

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10
Q

investigate the rate of conduction through various materials

A

add hot water to a tank. on the other side of the tank, attach equal lengths of materials of the same diameter. with vaseline, stick a tack on each one. The first tack to fall off bc the vaseline melted is the best conductor of heat - copper.

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11
Q

define convection

A

the movement of heat energy through liquids and gases due to the motion of the substance itself

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12
Q

investigate convection in liquids

A

conical flask with a lid on top. a little bit of dye on the bottom and some water. over a stand on a bunsen burner . as it heats up, the convection currents can be seen as the hot water moves up and colder water sinks down the sides.

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13
Q

How are convection currents involved in global warming?

A

cause the north atlantic drift which keeps seawater near ireland warm and prevents harsh winters. however it will reverse if global warming happens
-causes wind. if wind is warmed, violent storms will result

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14
Q

investigate convection in gases

A

a box with two chimneys on right and left. candle at bottom heats air, risinf out og right chimney. cool air comes down left chimney-convection currents can be seen with smoke from a piece of smouldering string held down the left chimney

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15
Q

define radiation

A

the transfer of heat energy via radiation waves that can travel through a vacuum.

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16
Q

what do all hot bodies emit?

A

a type of light known as rays of infrared radiation

17
Q

how is radiation used in life? 2

A

thermal imaging cameras detect warm objects (humans) in search and rescue operations.
-energy travels from sun to earth

18
Q

how is radiation involved in global warming?

A

black objects are good at absorbing and losing heat energy. white objects aren’t. If more snow and glaciers melt, more heat will be absorbed by the Earth from the Sun as there are less white objects. This causes more global warming

19
Q

investigate heat transfer by radiation

A

two flasks one white one black filled with hot water- note temp every 5 minutes. Black can better at losng heat - a better radiator of heat

20
Q

explain how conduction works

A

heat energy causes vibrating particles to pass on heat energy to other particles - on solids

21
Q

explain how convection works

A

warm particles rise, cooler particles fall to take their place : liquids, gases

22
Q

explain how radiation works

A

all warm objects release radiation as rays of infrared lights - all substances