Physics 3.0 Flashcards
(43 cards)
Thermal energy meaning
a measure of the total kinetic energy
of the particles in a substance.
When there is a temperature difference between two object, energy is always transferred from the … object to the …object
hotter to cooler
Conduction is…
thermal transfer by the vibration and collision of particles.
(in conduction)
The particles near the heat source start to vibrate.
These vibrations are passed onto the atoms next to them, which passes the vibrations through the material.
Metals are especially good thermal conductors because they contain
…….. These electrons can ….. and so transfer their energy more quickly
delocalised electrons
move and collide with ions further away from the source of heat
Specific heat capacity definition
the energy needed to raise the
temperature of 1 kg of a substance by 1 ºC.
Specific heat capacity equation
Change in thermal energy (J) = Mass (kg) x Specific heat capacity (J/kgoC) x Change in temperature (oC)
When we sweat, this liquid isn’t any
colder than our body temperature, yet it
helps to cool us down.
How?
It evaporates!
It takes energy for a liquid to evaporate. Your sweat takes this energy
from your body. So, as it evaporates, it takes energy (heat) from your
body, cooling your body down.
What tells you water is boiling?
Bubbles of water vapour/ steam are forming.
What is happening in terms of energy when you boil water?
Energy is being transferred to the water molecules by the flame
But kinetic energy (and therefore temperature) is not changing (remains constant).
The energy is going into overcoming intermolecular forces of attraction
between particles
Particles are moving further apart (separating)
The potential energy is increasing.
Specific latent heat definition
Specific latent heat of a material is the energy needed to change the state of 1 kg of the substance with no change in temperature.
Waves transfer energy without transferring matter. They are caused by…
oscillations.
Longitudinal waves
The object producing the wave vibrates in a direction parallel to the direction the wave transfers energy. e.g. sound waves, seismic p-waves
Transverse waves
The object producing the wave oscillates perpendicular to the direction of energy transfer. e.g. light waves, water waves
velocity of a wave meaning
the speed of a wave in the direction it is travelling
Peak/Crest
maximum point of the wave
Trough
minimum point of the wave
Wavelength
the distance from one point on one wave to the identical point on the next wave. The unit is metres (m)
Amplitude
the maximum distance of a point on the wave from its rest position
Frequency, f
The number of waves that pass a point each second. The unit is Hertz (Hz)
Period, T
The length of time it takes one wave to pass a given point. The unit is seconds (s)
Describe what happens to the pitch of the sound if you increase the frequency of it.
If you increase the frequency of a sound, the pitch gets higher
State the name given to sounds with frequencies above the range of human hearing
ultrasound
why does light not move quickly through solids?
as there are lots of particles squashed
together it becomes harder for the light to move through it, as a result the light slows down.
Transmit
pass through
