Physics Flashcards
(27 cards)
Give the equation for calculating weight
Weight = mass x gravity
Give the equation for calculating work done
Work done = force x distance
Define efficiency
A measure of the useful energy transferred by an object compared to the total amount of energy it uses.
Describe how the efficiency of a machine can be improved
Lubricate moving parts to reduce friction.
Secure all screws to reduce vibrations.
Use streamline shapes.
Give the equations for calculating power
Power = work done / time
Power = energy transferred / time
Define power
The amount of energy transferred by an object each second.
Give the unit of power
Watts (W).
Define thermal conductivity
Define thermal conductivity
The ability of a material to transfer energy by heating.
Define a conductor
A material with a high thermal conductivity (it’s good at transferring heat).
Define an insulator
A material with a low thermal conductivity (it’s bad at transferring heat).
Define conduction
The transfer of energy through a material by the vibration of its atoms.
Define convection
The circulation of a fluid caused by increasing its thermal energy.
Define specific heat capacity
The amount of energy needed to raise the temperature of a 1kg substance by 1 °C.
Describe how loft insulation reduces heat loss
Made from fiberglass which has a low thermal conductivity. The material is mainly air, which stops conduction. The glass fibres stop convection.
Describe how cavity wall insulation reduces heat loss
Made from insulating foam. Contains air pockets to stop conduction.
Describe how double glazing reduces heat loss
Vacuum between two panes of glass. Reduces conduction and convection
Describe how aluminium foil behind a radiator reduces heat loss
Shiny surface reflects heat back into the room.
Give factors that affect how quickly a substance heats up
Mass, thermal energy applied, specific heat capacity.
specific heat capacity equation
thermal energy change = mass x specific heat capacity x temp change
Why would you use a bar chart drawn rather than a line graph?
if the data is categoric
Mechanical work
Forces and waves
El ectrial work
Electric currents
Electromagnetic radiation
Light
Heating
Conduction and convection
