Heat

Question 1

What is heat radiation?

Answer 1

Thermal radiation is electromagnetic radiation generated by the thermal motion of particles in matter. Thermal radiation is generated when heat from the movement of charges in the material is converted to electromagnetic radiation. All matter with a temperature greater than absolute zero emits thermal radiation.

Question 2

What is head conduction?

Answer 2

Conduction is where heat is transferred through molecules and atoms, and moves to neighbouring molecules. this occurs more readily in liquids and air, where the particles are closer.

Question 3

What is heat absorption?

Answer 3

When a colour absorbs light, transferring it into thermal energy, also known as heat. Lighter colours produce less thermal energy in comparison to darker colours due to the fact they absorb heat less quick.

Question 4

What are three types of radiators?

Answer 4

Steam Radiators
Electric Radiators
Aluminium Radiators

Question 5

What is heat transmission?

Answer 5

Heat transfer is a discipline of thermal engineering that concerns the generation, use, conversion, and exchange of thermal energy between physical systems. Heat transfer is classified into various mechanisms, such as thermal conduction, thermal convection, thermal radiation, and transfer of energy by phase changes.

Question 6

How does an aluminium radiator function?

Answer 6

These radiators are made by brazing thin aluminum fins to flattened aluminum tubes. The coolant flows from the inlet to the outlet through many tubes mounted in a parallel arrangement. The fins conduct the heat from the tubes and transfer it to the air flowing through the radiator.

Question 7

How does a steam radiator function?

Answer 7

Steam radiators are connected to a boiler given the task of heating up water. The boiler heats water until it forms into steam. The steam then travels up through the vertical pipe to the radiator where the thermal energy is given off through the fins.

Question 8

How does an electric radiator function?

Answer 8

When an electrical current is applied, the electrons jostle together as they move through the narrow length of wire, creating friction and heat as they move. As the wire heats the oil, warmth is transferred to the radiator body, which in turn heats the air volume in the room.

Question 9

What is heat reflection?

Answer 9

Reflection occurs when incoming solar radiation bounces back from an object or surface that it strikes in the atmosphere, on land, or water, and is not transformed into heat. The proportion of incoming solar radiation that is reflected by the Earth is known as its albedo. Overall, Earth reflects about 29% of the incoming solar radiation, and therefore, we say the Earth’s average albedo is 0.29.

Question 10

What are good and bad emitters and absorbers of heat?

Answer 10

Dull dark matt surfaces are good absorbers and good emitters of radiation. For example the cooling fins on the back of a refrigerator.

Light, shiny surfaces are poor absorbers and poor emitters of radiation. This is why it is best to wear bright white clothes on a hot day as they reflect the heat and reduce absorption of the heat energy.

Question 11

Convection of heat in a house:

Answer 11

On hot days, heat is conducted into your home through the roof, walls, and windows. … Convection is another means for the heat from your walls and ceiling to reach you. Hot air naturally rises, carrying heat away from your walls and causing it to circulate throughout your home.

Question 12

Convection of heat in a house:

Answer 12

On hot days, heat is conducted into your home through the roof, walls, and windows. … Convection is another means for the heat from your walls and ceiling to reach you. Hot air naturally rises, carrying heat away from your walls and causing it to circulate throughout your home.

Question 13

Convection of heat in nature:

Answer 13

One of the most common examples of natural convection is the phenomena of the sea and land breeze. Sea breeze: This phenomenon occurs during the day. The sun heats up both the sea surface and land. … Land Breeze: This phenomenon occurs during the night when the situation reverses.

Question 14

Convection of heat in a room:

Answer 14

Convection currents are created when the air above your radiator heats and then cools and is then heated again. This process happens continuously whilst you have your heating on and the current moves the heat around the room making it nice and warm and toasty.

Question 15

Convection of heat in a refrigerator:

Answer 15

Refrigerators operate using convection by circulating the gas through the copper lines inside of the refrigerator or freezer compartment. The lines, and the gas contained within them, absorb the heat contained in the refrigerator and freezer compartments, and are circulated back outside of the unit.

Question 16

Convection of heat in thermals:

Answer 16

When a fluid, such as air or a liquid, is heated and then travels away from the source, it carries the thermal energy along. This type of heat transfer is called convection. The fluid above a hot surface expands, becomes less dense, and rises.

Question 17

Convection of heat in a magnetic field:

Answer 17

When the magnetic field is applied to magnetic fluid flow, the heat transfer coefficient largely increases in the area where magnet field exists comparing with heat transfer coefficient under no magnetic field. This heat transfer becomes large with increasing magnetic field.

Question 18

How does sweating, being flush, and goosebumps relate to heat energy?

Answer 18

When the hypothalamus senses an increase in core temperature it will act by increasing blood flow to the skin, stimulating the sweat glands. The result is an increase in the rate of water lost through sweating. Whilst increasing the blood flow to the skin, it increases the temperature of the body as it rises the blood, making the red hue more visible.
For Goosebumps, the minute muscles under the surface of the skin called arrector pili muscles (attached to an individual hair follicle) contract (piloerection), lift the hair follicle upright. This makes the hairs stand on end, which acts as an insulating layer, trapping heat. This is what also causes goose bumps since humans do not have very much hair and the contracted muscles can easily be seen.
Arterioles carrying blood to superficial capillaries under the surface of the skin can shrink (constrict), thereby rerouting blood away from the skin and towards the warmer core of the body. This prevents blood from losing heat to the surroundings and also prevents the core temperature dropping further. This process is called vasoconstriction. It is impossible to prevent all heat loss from the blood, only to reduce it. In extremely cold conditions, excessive vasoconstriction leads to numbness and pale skin. Frostbite occurs only when water within the cells begins to freeze. This destroys the cell causing damage.

Question 19

How do animals adapt to hot climates?

Answer 19

Many animals in hot climates lower their body temperature and with it their metabolic rate, entering an almost dormant state. They become inactive, reducing their response to the heat and their water loss through perspiration, breathing and relieving themselves. By merely flapping their ears, elephants can reduce their body temperature by 10 degrees Fahrenheit or more. Air permeates the thin skin of the elephant’s ears, thereby cooling blood as it passes though a web of vessels inside the ears before returning to the body. When the temperature is very hot and especially when it is humid, everything heats up…including a dog’s body. His body responds by trying to cool off and it basically attempts to use conduction, convection, radiation, and evaporation. A dog will seek a cool place in the shade to lie down to absorb the coolness (conduction). His blood vessels will dilate in his skin and tongue bringing hot blood close to the surface radiating his internal heat. He will seek out fans or breezes to blow air to transfer the heat from body to air (convection). He will pant to bring air into his upper respiratory system to evaporate water from his mucous membranes. He will drink a lot of water to compensate for the evaporation.

Question 20

How do animals adapt to cold climates?

Answer 20

Animals that adapt to the cold weather often change their appearance. They grow warmer fur or feathers and sometimes change colour. Some animals change colour to camouflage themselves against the snow. These animals can find food in winter, even though there isn’t much food around. Emperor penguins have four layers of overlapping feathers that provide excellent protection from wind, and thick layers of fat that trap heat inside the body. They also have specially arranged veins and arteries in these body parts, which helps recycle their body warmth.