Physics Unit 1

Physics Unit 1

1. P1A Energy and Elec.

   • Energy Sources
     • Non-Renewable= Fossil fuels, Nuclear, Bio fuels
     • Renewable= Solar, Tidal, Geo thermal, Wave, Hydroelectric, wind
   • Energy cannot be created, or destroyed
   • Surfaces
     • Matte=bumpy(High SA:V)
     • Shiny=very smooth(low SA:V)
     • Black: absorbs heat and emits heat much quicker than other colours
     • Silver: reflect infrared radiation better, therefore don't get as hot, but stay hot for longer as they aren't very good at emitting
   • U-Values
     • The higher the U-value, the higher the heat flow, which is bad for insulation
     • Heat lost per second= U value X area X temperature difference
   • Specific Heat Capacity
     • The specific heat capacity of a substance is the amount of energy in joules that is needed to raise the temperature of 1Kg of the substance by 1 degrees C
     • Energy needed(J) = specific heat capacity(J/kg degrees C) X Mass(Kg) X Change in temperature( degrees C)
   • Efficiency= useful energy out/total energy in
     • Efficiency=useful power out/total power in

2. P1b Waves

   • Ultrasound= above 20,00Hz
     • Pre-natal Scanning
     • Kidney stone breakdown
   • Human Range= 20 to 20,000Hz
   • Infrasound= Below 20Hz
   • wave speed(m/s) = frequency(Hz) X Wavelength(m)
   • Types
     • Transverse= waves that have sideways vibrations
     • Longitudinal= waves that have vibrations along the same line
   • Red Shift and Big Bang
     • CMBR= Cosmic microwave background radiation
     • Red Shift is believed to be caused by the movement of everything away from eachother, stretching the light waves along so they are red-shifted
   • Kinetic Energy(J) = half X Mass(Kg) X velocity2(m/s2)
   • Reflections/Refractions
     • angle of incidence=angle of refraction
     • if the angle of incidence is less than the critical angle, refraction will take place.
     • if the angle of incidence is equal to or greater than the critical angle, total internal reflection will take place
     • The refractive index determines how dense a medium is.

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