Heat energy

Question 1

What is heat

Answer 1

Heat energy is the result of the movement of tiny particles called atoms in solids, liquids and gasses. Heat energy can be transferred from one object to another. The transfer or flow due to the difference in temperature between the two objects is called heat.

Question 2

What is heat energy flow?

Answer 2

Heat is the flow of energy form a higher temperature to a lower temperature.

Question 3

What is heat and temperature during the heating of water?

Answer 3

Heat: the heat energy from the stove burner warms up the water.
Temperature: the thermometer measures the temperature of the water.

Question 4

3 heat energy information?

Answer 4

Heat is a form of energy
Heat is due to the molecules or vibration of particles.
Faster particles have more heat then slow particles

Question 5

What is Temperature?

Answer 5

Temperature is a measurement

Question 6

When do Substances expand and contract?

Answer 6

Substances expand (increase in size) when they get warmer, and they contract (decrease in size) when they get cooler.

Question 7

Example of expansion using a Thermometers?

Answer 7

Thermometers work because the liquid inside them expands and rises up the tube when it gets hotter.

Question 8

How are Expansion joints helpful?

Answer 8

Expansion joints like this allow bridges to expand and contract without damage

Question 9

What do the particles do?

Answer 9

When substances expand or contract, their particles stay the same size. It is the space between the particles that changes

Question 10

What do the particles do in a solid when there heated?

Answer 10

The particles in a solid vibrate more when it is heated, and take up more room.

Question 11

What do the particles do in liquid when there heated?

Answer 11

The particles in a liquid move around each other more when it is heated, and take up more room

Question 12

What do the particles do gasses when there heated?

Answer 12

The particles in a gas move more quickly in all directions when it is heated, and take up more room

Question 13

What happens to the space of the particles when they expand or contract?

Answer 13

The space between particles changes when a substance expands (or contracts)

Question 14

Does the particles expand or contract?

Answer 14

The particles themselves never expand.

Question 15

How is Thermal expansion caused?

Answer 15

It’s caused by heating solids, liquids or gasses, which makes the particles move faster or vibrate more (for solids). This means that the particles take up more space so the substance expands.

Question 16

How is heat (thermal) energy created?

Answer 16

Heat (thermal) energy is created by the movement of particles (atoms) that produces heat.

Question 17

How does heat energy increase?

Answer 17

Heat (thermal) energy increases as temperature increases because as temperature increases, atoms move faster (have more kinetic energy)

Question 18

When is heat transferred?

Answer 18

Heat (thermal energy) is transferred from one object to another when the objects are at different temperatures.

Question 19

What is the amount of heat transferred?

Answer 19

The amount of heat (thermal energy) that is transferred when two objects are brought into contact depends on the difference in temperature between the objects.

Question 20

How does thermal energy move?

Answer 20

Thermal energy always moves from warmer to cooler objects. The warmer object loses thermal energy and becomes cooler as the cooler object gains thermal energy and becomes warmer. Energy will continue to move from a warmer object to a cooler object until both have the same temperature.

Question 21

What are the three ways heat can occur?

Answer 21

Convection
Conduction
Radiation

Question 22

What is Conduction?

Answer 22

Conduction is the transfer of heat by direct contact (particles collide). Conduction occurs most easily in solids and liquids

Question 23

Why is conduction easier in solids and liquids?

Answer 23

Atoms and molecules are closer together in solids and liquids. So, the particles need to move only a short distance before they bump into one another and transfer energy.

Question 24

Example of Conduction?

Answer 24

Ice melting in a hand: Faster moving molecules in your warm hand bump against the slower moving molecules in the ice. Thermal energy moves from your warmer hand to the colder ice. The slow moving molecules in the ice move faster.

Question 25

What is Convection?

Answer 25

It involves the transfer of heat through the movement of fluids (liquids or gasses) caused by density differences within the fluid.

Question 26

How does convection occur?

Answer 26

In convection, heat is transferred through the movement of a fluid. This movement occurs
because when a fluid is heated, it becomes less dense and rises while cooler, denser fluid
sinks. This process creates a circulating motion called a convection current.

Question 27

What is Convection in a kettle?

Answer 27

The water molecules at the bottom of the kettle gain heat energy from the flame and vibrate faster and move further apart. Their density decreases and the hotter particle rise to the top of the kettle. The colder less dense molecules move into replace the hotter particles. This continues until all the water is the same temperature.

Question 28

What is Natural Convection?

Answer 28

Natural convection occurs when the fluid is moved just by density differences caused by temperature differences. For example, when you heat a pot of water on a stove, the water near the bottom gets warmer and rises to the top while the cooler water near the surface sinks, creating a convection current.

Question 29

What is Atmospheric Convection?

Answer 29

Convection is also prevalent in the atmosphere and is responsible for many weather phenomena. It drives the formation of clouds, thunderstorms, and the global circulation of air masses.

Question 30

What is Heat Transfer?

Answer 30

Convection plays a significant role in transferring heat energy. When a fluid moves past a solid surface, such as air flowing over a hot plate, it absorbs heat from the surface and carries it away. This process aids in cooling the solid object.

Question 31

What is Applications?

Answer 31

Convection is present in many everyday situations. For instance, air circulation in a room due to temperature differences is a form of natural convection. Additionally, convection is used in heating and cooling systems, such as radiators, air conditioners, and refrigerators, where fluids transfer heat.

Question 32

What is Forced Convection?

Answer 32

Forced convection involves using external ways, such as fans or pumps, to move the fluid motion and increase heat transfer. For instance, a computer’s cooling fan helps remove heat by blowing air across the hot components, increasing the heat transfer rate through convection.

Question 33

when does heat radiation travel best?

Answer 33

Heat radiation travels best through a vacuum.

Question 34

What happens when heat radiation hits matter?

Answer 34

When it hits matter (solid, liquid or gas) it is absorbed (taken in).

Question 35

What happens to heat radiation energy?

Answer 35

Its energy is transferred to the particles of the matter that absorbed it, making them move faster. This warms the matter up.

Question 36

example of heat radiation?

Answer 36

When you feel the sun’s warmth on your skin.

Question 37

What are the three words that explain heat radiation?

Answer 37

Absorbing, Emitting and Reflecting.

Question 38

Are all surfaces good at absorbing heat radiation?

Answer 38

Not all surfaces are equally good at absorbing heat radiation.

Question 39

What are the best surfaces at absorbing heat radiation?

Answer 39

dull, black surfaces are the best.

Question 40

What are the worst surfaces at absorbing heat radiation?

Answer 40

shiny white or silvery surfaces are the worst

Question 41

What does shiny surfaces do with heat radiation?

Answer 41

White, shiny surfaces are best at reflecting heat radiation rather than absorbing it.

Question 42

What is the difference between black and white clothes during hot weather?

Answer 42

If you wear dull black clothes in warm sunshine you get hot very quickly. White clothes reflect most of the heat, so keep you cooler!

Question 43

Why are kettles white or slivery rather than dull black?

Answer 43

This is because dull black surfaces are best at emitting (giving out) heat radiation as well as absorbing it. So your kettle is white or silvery for a reason – it keeps its heat in better that way!

Question 44

How do a Grill work?

Answer 44

Grills, and old-fashioned electric bar fires (“radiant heaters”) also give out heat radiation. In a grill, the food absorbs the radiation, which heats it up.

Question 45

How do fire work in the house?

Answer 45

The fire, used in the house is absorbed by the furniture and the walls due to radiation, which then warms the air by conduction and convection to warm the room up.

Question 46

What is the amount of radiation given out by objects?

Answer 46

The amount of radiation given out by objects depends on their temperature and their surface. The hotter the object the more energy it radiates and the bigger the heat difference between the hot object and the surroundings the faster the heat transfer.

Question 47

Is radiant energy a continuous process?

Answer 47

All objects also receive radiation and the exchange of radiant energy is a continuous process. Therefore a body at constant temperature is receiving and radiating energy at the same rate.

Question 48

What is heat?

Answer 48

Heat is a word that we use in everyday language to describe the energy stored in a substance. A warm object would have a larger energy store than a cold one.

Question 49

What do we mean when we say ‘the cold’?

Answer 49

When we talk about ‘the cold’ we usually mean the opposite of ‘heat’.
Cold is a word we use in everyday language to describe a lack of energy stored in a substance. Objects feel cold if energy is transferred from your skin to the object.

Question 50

Heat and ‘the cold’ are not substances. Can they move from one place to another?

Answer 50

no

Question 51

What move between the inside and the outside of the house?

Answer 51

Air particles move between the inside and outside.
The warmer air from the house has a larger energy store. These particles move around more than the particles in the colder air outside. This movement increases the distance between the particles and means that the warm air inside the house is less dense than the cold air outside.

Question 52

In which direction will the air particles move?

Answer 52

The warmer air inside the house will rise out of the door because it is less dense than the cold air. It will be replaced by cold air moving in through the door at the bottom. This is called convection.

Question 53

How to Minimize Convection?

Answer 53

The outside walls of houses often have a space between the two layers of bricks called a cavity.
The air in the space acts as an insulator, reducing energy transfer due to conduction. However, convection currents can still form within the cavity, causing energy transfer from the house to the surroundings. An insulating material can be pumped into the cavity. The insulating material has pockets of air that reduce conduction. The fibers of the insulation prevent the air from circulating inside, reducing energy transfer by convection.

Question 54

How to Minimize Conduction?

Answer 54

The particles in a liquid and gas are further apart than the particles in a solid. This makes it more difficult for liquids and gasses to transfer energy through contact between particles, making them poor conductors.
Some solids that are good insulators are shown below.

Question 55

How to Minimize Radiation?

Answer 55

A space blanket is a lightweight blanket made of thin, reflective plastic, often found in first aid kits. The reflective surface reflects about 80% of the radiation emitted from a person’s body back to them, reducing energy transfer to the surroundings. Reflective foil can be fitted inside or on walls. This reduces energy transfer to the surroundings by reflecting the radiation back into the building.