Heat, Sound and Light Flashcards
What’s heat?
Heat is the energy that flows between two substances of different temperature
what direction does heat flow?
From a warm substance to a cold substance
Which defines the average kinetic energy of a system’s particles?
temperature
A hot metal plate at 150°C has been placed in air at room temperature. Which event would most likely take place over the next few minutes?
The air molecules that are surrounding the metal will speed up, and the molecules in the metal will slow down.
What is a exothermic reaction?
A reaction that releases heat
What is a endothermic reaction?
A reaction that absorbs energy
In an exothermic reaction, the environment gets?
hotter
In an endothermic reaction, the environment gets?
colder
Uses of endothermic reactions?
ice packs
Uses of exothermic reactions
hand warmers
Examples of exothermic reactions
combustion, oxidation, neutralization
The process of a solid to a gas is called..
sublimation
Example of sublimation
dry ice
The process of gas to a solid is called..
deposition
What is heat/thermal energy?
Kinetic energy of the particles inside matter.
Unit of thermal energy
Joules (J)
Difference between temperature and heat
Temperature: measure of
how hot the object is
measured in C*
Heat: The total kinetic energy of the particles in a matter
Measure in Joules (J)
What thermal equilibrium
when the heat transfers from a hot object to a cool object until both the objects have the same temperature
Which one has more heat:
A bowl of soup having a temperature of 75°C or the sea at Portrush has a summer temperature of 17°C.
The sea because it has more particles than the soup therefore more thermal energy
What’s heat transfer?
The transfer of heat from a higher temperature to a lower temperature
Define Conduction
flow of heat energy from high temperature to low temperature without overall movement of the material
Which particle model does conduction mainly occur
Solid
What two particle models are really bad conductors (Insulators)
Liquid and gas
Why are metals good conductors?
They have free electrons
why are hair, fur, feathers and wool are good insulators
because they trap heat
What’s convection?
flow of heat energy from high temperature to low temperature by movement of a fluid.(liquid and gases)
Describe convection
When part of a liquid or gas is heated it expands, becomes less dense and rises. It is replaced by the cooler, denser fluid.
This liquid or gas is in turn heated, expands becomes less dense and rises. Therefore creating convection currents
What is radiation?
transfer of heat from high to low temperature through INFARED radiation
how does radiation travel
it travel through vacuum with no medium (Sun radiates heat to earth through vacuum)
What are the best absorbers and emitters of heat
Dull Black Surfaces
What are poor absorbers and emitters of heat but GOOD REFLECTORS
Shiny Surfaces
how does radiation relate to greenhouse
when the suns radiation warms up the earth it gets reflected to the atmosphere which in turn reflects to space or CO2 present in the atmosphere absorbs it cause the earth to warm up
how does vacuum flask
A vacuum flask uses a vacuum and reflective coating to minimize heat transfer by conduction, convection, and radiation, keeping liquids hot or cold for extended periods.
How does sound travel?
Sound travels in waves(it needs a medium-air)
How is sound created?
Sound is created by vibrations
what are the different types of sound waves and explain each
Longitudinal wave-parallel to the direction in which the waves travel
Transverse wave-perpendicular to the direction in which the waves travel
sound travels by several compressions and rarefactions
T/F
TRUE
How do you know that the sound has high amplitude by looking at its compressions and rarefactions
The more compressed the air molecule, the higher the pressure which means the higher the volume
How is sound measured?
decibels (dB)
how to identify its high pitch by looking at the waves
it would have more frequency
why in space no one can hear you scream
sound travels through a medium such as air but there’s no medium on space that’s why no one can hear u scream on space
which colour has the longst wavelenght
RED
Whta colour has the shortest wavelength
Violet
what color refracts the least
RED
How does light travel?
Light travels in straight lines
how does light change direction
Using reflections and refractions
what is the law of incidence
angle of incidence = angle of reflection
What type of waves are light?
Transverse
Light waves change ______ when they pass across the boundary between two substances with a different density, such as air and glass. This causes them to change direction, an effect called refraction.
Speed
what happens to the Light passing from a less dense to a more dense medium?
the ray bends toward the normal.
what happens to the light passing from a more dense to a less dense medium
the ray bends away from the normal.
What is dispersion?
The splitting of white light into its colours
Objects appear black in white light because…
they absorb all colors and reflect none.
concave lens?
spreads light out
Convex lens?
bends light inwards
what are convex lens used for?
To magnify small objects
what are concave lens used for?
used in glasses for short sightedness
