physics mock exam

physics mock exam

1. speed, distance, time graphs, calculations

   • speed=distance travelled/time taken
     • d=s*t
     • t=d/s
   • distance time graphs
     • speed=gradient=d/t=?m/s

2. terminal velocity

   • the fastest speed a falling object has

3. Ohms law

   • the current that flows through a conductor is directly proportional to the potential difference across its ends, provided its temperature remains constant

4. mains electricity

   • fuse box contains fuses or curcuit breakers
   • live wire:provides the path along which the eletrical energy from power stations travel
   • neutral wire: completes the curcuit
   • earth wire: no current through it, protects you from faults
   • 230v is the mains electricity to uk homes
   • the casing is made from plastic as its a good insulator

5. fuses

   • fuses have a low melting point
     • if it melts the curcuit breaks
       • prevents you getting a shock
   • the curcuit breakers opens to make a curcuit incomplete if a too large current flows through
   • double insulation helps stop eletric shocks
     • toasters etc have a high resistance
   • power(watts)= current(I) (in amps)*voltage(V) (in volts)
     • p=i*v

6. forces

   • an object will not change velocity unless theres an unbalenced force
   • force (N)= mass(M)(in KG)*acceleration (A) (in m/s2)
   • force=(mv-mu)/time taken

7. momentum

   • momentum(kg in m/s)=mass (m in kg)*velocity (in m/s)
   • collisions
     • momentum change: force*time= increase in acceleration
     • elastic collisions: colliisions where no kinetic energy is lost by transformed into other energy types
     • momentum before=momentum after
     • newtons law of motion
       • things dont speed up or slow down or change direction unless you push or pull them
       • when you push something it pushes back just as hard but in the oppisite direction

8. acceleration

   • acceleration=change in speed/time taken
   • rate at which an object changes speed

9. moments

   • moment of force (Nm)=force (N)*perpendicular distance from pivot (d)(in m)
   • an object will be in balence if sum of antilclockwise moments=sum of clock wise moments

10. types of orbit

    • low polar orbit
      • weather
        • spying
          • observing earths surface
    • geo stationary statellites
      • stationed over equator
      • doesnt move
      • communtications
        • gps
    • orbital speed: 2*3.142(pi)*orbital radius/time period
      • 23.142r/t

11. light

    • reflection
      • when a ray of light strikes a mirror it is reflected so that the angle of incidence is equal to the angle of reflection
      • mirrors are used to change the direction of ray of light
      • images are created from rays of light in mirror reflections
        • virtual thing=images were light doesnt pass
        • real images= images created with light passing through them
    • refraction
      • light travels at 300,000,000m/s
      • the change in speed may cause ray to change direction. this is refraction
      • refractive index
        • to find the angles of refrection
        • n=sin i/sin r
      • total internal reflection
        • when a ray of light passes from an optically more dense medium to an optically less dense medium (eg glass to air) the light is reflected away from the normal
        • sin c=1/n
    • transverse waves can be feflected, refracted and diffracted
    • ray diagrams

12. magnetic fields

    • volume of space where magnetism can be detected
    • cannot be seen but with iron filings you can see it
    • when north and south poles are placed near each other there is an almost uniform field between the two poles

13. sound

    • sound waves
      • as a speaker comes to the right it pushes air molecules together creating a compression
      • this is a longitude sound wave and can be reflected, refracted and disfracted
    • speed of sound
      • echoes
        • divide distance by time
      • resonance tube and tuning forks
      • oscilloscope
    • reflected sound wave is called an echo

14. electromagnetic spectrum

    • visiable light
    • gamma radiation
      • killing cancer cells
      • shortest wave length
    • x rays
      • medical images of bones
    • ultraviolet radiation
      • sunbeds
    • visiable light
      • seeing
    • infrared radiiation
      • optical fibre radiation
    • microwaves
      • cooking
    • radio waves
      • tv signals
      • longest wave length

15. energy transfers

    • we need to convert energy from place to place to be useful
    • energy becomes concerted an wasted
    • eg: heating water the engery converted is lost as its not doing what we want making the water hot

16. heat transfers

    • can be transferred by conduction, convention and radiation
      • heat energy is transferred by conduction
      • liquids and gases by convention
        • Convection occurs when particles with a lot of heat energy in a liquid or gas move and take the place of particles with less heat energy.
      • All objects give out and take in thermal radiation, which is also called infrared radiation.

17. radiation

    • plum pudding model
      • J.J. thompson found negatively charged particles(electrons)
    • nuclear model
      • alpha particles go straight through foil
      • alpha particles werent deflected
      • most the atom is an empty space
      • most the mass is in the nucleus
      • nucleus of an atom has a positive charge

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