paper 1

paper 1

1. topic 1

   • scalar and vector
     • have magnitude
       • mass , density, speed , energy ,distance
         • speed x time = distance
           • distance travelled is the area under a velocity vs time graph
         • speed = distance / time
     • having magnitude and direction
       • force ,weight ,momentum,acceleration ,displacement ,velocity
         • velocity is speed in a stated direction
         • acceleration = velocity / time taken
           • acceleration is the gradient of a velocity vs time graph

2. topic 2

   • newtons first law
     • unbalanced forces result in acceleration . If the resultant force is zero the plane will be moving at a constant velocity
   • newtons 2nd law
     • mass x acceleration = force
     • mass x gravitational field strength = weight
     • the larger the force on the object the greater the acceleration for the same mass
       • the greater the mass of the object the less the acceleration for the same force
   • momentum
     • change in momentum / time = force
     • mass x velocity =momentum
     • large changes in momentum over a short time increases the forces experienced
   • newtons 3rd law
     • action and reaction forces are equal in size and opposite in direction
   • stopping
     • stopping distance is made up of the sum of thinking distance and braking distance

3. topic 3

   • KE and GPE
     • 1/2 x mass x velocity (squared )= kinetic energy
     • often will be asked about roller coasters , swing ,a pendulum or a bouncing spring .
       • in each case energy changes from GPE to KE and back again through the total energy of the system remains constant
   • energy transfers
   • energy storage
     • energy can be stored in different forms and then transferred .
       • car braking ; kinetic--- heat + sound
       • kettle boiling = electrical --- thermal
       • skydiver : G.P.E -- kinetic energy
       • hammer and nail = kinetic ---- sound and thermal
       • up hill : kinetic ----- gravitational potential ( G.P.E )
   • efficiency
     • efficiency = ( useful energy transferred by the device ) '/. ( total energy supplied to device )
     • useful energy --- is the energy that ends up in the form that the device is used for light so light energy is the useful form .
     • wasted energy - is the energy that ends up in the form that the device is not used for e.g a light bulb is not used to heat a room so heat energy lost to the surroundings is a wasted form
   • sources of energy
     • oil (n)
     • coal (n)
     • gas (N)
     • nuclear fission ( n)
     • tidal ( r )
     • solar ( r )
     • Biofuel (r)
     • (n) means will run out
     • in the future the reliance on fossil fuels will decrease and the use of renewables will increase

4. topic 4

   • frequency x wavelength = wave speed
   • distance/ time = wave speed

5. topic 5

   • refraction
     • the amount a wave is refracted at a boundary can vary with wavelength
       • for e.g: in a prism the longer red wavelength is refracted less than the shorter blue wavelegth
         • the same is true for other materials which may absorb ,transmit ,refract or reflect waves in ways that also vary with wavelength
   • electromagnetic waves
     • our eyes can only detect a limited range of frequecies
       • decreasing wavelength
       • increasing frequency
       • increasing danger
   • harm of em waves
     • microwaves - interal heating of body cells
     • uv ; damage to surface cells and eyes , leading to skin cancer and eye conditions not burns
     • infared : skin burns
     • xrays and gamma rays : mutation or damage to cells in the body
     • the dangers of electromagnetic radiation increases with increasing frequency - from radio through visible to x-rays and gamma
   • uses of EM waves

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