Transfer of heat energy and it's effects Flashcards
What is the SI unit of temperature?
Kelvin (K)
What happens when two objects are in contact regarding heat energy transfer?
Heat energy is transferred from a hotter region to a colder region until both are the same temperature.
What are the effects of transfer of heat energy on an object?
Causes objects or substances to expand or contract.
What is expansion in terms of heat energy?
Causes objects or substances to gain heat and expand, increasing its volume.
What is contraction in terms of heat energy?
Causes objects or substances to lose heat and contract, decreasing its volume.
How do metal railway tracks respond to heat?
They gain heat and expand during hot weather, with expansion gaps to prevent buckling.
What percentage of Earth’s heat energy do oceans absorb?
More than 90%.
What is a consequence of global warming on oceans?
Oceans absorb more heat energy, causing them to expand and sea levels to rise.
How does placing a jar’s lid in hot water help open it?
The metal lid expands more than the glass jar, making it less tight.
What is a bimetallic strip?
Made of two metals that expand at different rates upon the same temperature change.
Which metal expands and contracts more: brass or steel?
Brass.
What is the function of bimetallic strips in thermostats?
Helps keep the temperature of an appliance constant.
How does a bimetallic strip in an electric iron work?
The strip bends downwards when heated, opening the circuit and switching off the iron.
What does a food thermometer measure?
The temperature of food to ensure it is cooked to the right temperature.
Describe the structure of a liquid-in-glass thermometer.
A narrow glass tube sealed at both ends with a bulb filled with mercury or alcohol.
What happens to the liquid in a liquid-in-glass thermometer when temperature increases?
The liquid expands and rises up the narrow tube.
What effect does heating air in a hot air balloon have on its density?
It decreases the density, causing the balloon to rise.
What are the three methods of heat energy transfer?
Conduction, Convection, Radiation.
What is conduction?
The transfer of heat without the physical movement of the medium.
What is the role of free electrons in conduction?
They move throughout the metal to transfer thermal energy from the hotter to cooler parts.
What is convection?
The transfer of heat energy from one place to another by the physical movement of a medium.
What occurs to the density of water when it is heated?
Its density decreases, causing warmer water to rise.
What is radiation?
The transfer of thermal energy in the form of waves that does not require a medium.
What type of wave is emitted when a body radiates thermal energy?
Infra-red radiation.
