Chapter 10- Transfer of Heat and its Effects Flashcards
Understand the transfer of heat and its effects
SI Unit of Temperature
K
How does heat transfer work
Heat is transferred from the hotter object to the colder object until both of them reaches the same temperature
Define expansion
When an object gains heat and increases in volume
Define contraction
When an object loses heat and reduces in volume
Left space in certain places in the world (e.g.railroads) because of?
Expansion and the chance for train racks to buckle
Usages of bimetallic strips
1)Thermostat
2)fire alarm
3)Oven
How does bimetallic strips work (in general)
In the bimetallic strip, the brass side will expand more than the steel side. This causes an open circuit, switching off whatever the bimetallic strip is connected to. When the bimetallic strip cools down, it will become straight again and allow the contacts to touch for a closed circuit.
How does the bimetallic strip work in a food thermometer?
One end of nthe bimetaqllic strip will be attached to a pivot or fixed end, and the other point will have a pointer connected to it. Due to the different expansion rates of the metals, it will cause the coil to unwind or tighten, allowing the pointer to move appropraitely on a scale.
How does liquid in glass thermometers work
When the bulb of a thermometer gains heat, the liquid inside will expand more than the glass, causing the liquid to rise up in the thermometer
How do hot air balloons work
Since the air in the balloon is heated, its volume increases, but the mass of the air does not change due to conservation of mass, leading the hot air balloon to be less dense than the air and rise
Which states of matter can perform conduction, and which state of matter performs it best
All 3. Solid.
Define conduction
Conduction is the transfer of heat through contact, without the physical movement of the medium
Why does it feel colder when you touch a metal can then a milk carton although they are at the same temperature
This is due to the fact that the metal can is a better conductor of heat, thereby allowing more heat to be transferred from our hands at a faster rate
Which type of solid is the best conductor of heat
metals
Why are solids generally better conductors of heat then liquids
This is due to the fact that the particles are arranged more closely to one another, allowing heat transfer to happen more quickly
Define convection
Convection is the transfer of heat from one place to another through the physical movement of a medium
In which states of matter can convection be effective in
Fluids (liquids and gasses)
How does a bunsen beaker perform convection
Particles of water get heated by the flame through conduction. Particles gain TE, leading to greater distances between particles. This will induce the increase in volume but conservation of mass, leading the water to be less dense and rise to the top, while causing the cool and denser air at the top to then sink. The air is denser at the top as heat has not reached it yet. leading it to sink to the bottom, thus forming a convection current. Convection will occur until the temperature throughout the water is equal
SAME EXPLANATION FOR AIR
How does the sun transfer heat to earth
Through radiation
What is the greenhouse effect.
When greenhouse gasses trap heat in the atmosphere of earth to support life
What are factors affecting the rate of conduction
The level of how well an object conducts heat
What are factors that affect radiation
1) Temperature of Object (higher temperature euqates to higher radiation)
2) Surface area of object (larger surface area leads to higher rate of radiation)
What are black, dull materials good for in terms of radiation
Absorption of radiation and emission of radiation
What are white shiny objects poor in in terms of radiation
Absorption and radiation
How do sea breezes occur
IN DAY When the sun heats up the land, it well make the air on top of it hotter as well, causing it to expand due to faster moving particles and lower FOA. This causes the density of the air above the land to decrease, and cool down above the sea. Then it moves back onto land and the cycle occurs again.
How do land breezes occur
AT NIGHT When the layer of air above the sea is warmer, it will become less dense and rise due to expansion, which resulted from faster particles and weaker FOA. This air will then cool above land and move back into the warmer ocean, forming a convection cycle
