physics mock exam

speed, distance, time graphs, calculations
1. speed=distance travelled/time taken
  1. d=s*t
  2. t=d/s
2. distance time graphs
  1. speed=gradient=d/t=?m/s
terminal velocity
1. the fastest speed a falling object has
Ohms law
1. the current that flows through a conductor is directly proportional to the potential difference across its ends, provided its temperature remains constant
mains electricity
1. fuse box contains fuses or curcuit breakers
2. live wire:provides the path along which the eletrical energy from power stations travel
3. neutral wire: completes the curcuit
4. earth wire: no current through it, protects you from faults
5. 230v is the mains electricity to uk homes
6. the casing is made from plastic as its a good insulator
fuses
1. fuses have a low melting point
  1. if it melts the curcuit breaks
    1. prevents you getting a shock
2. the curcuit breakers opens to make a curcuit incomplete if a too large current flows through
3. double insulation helps stop eletric shocks
  1. toasters etc have a high resistance
4. power(watts)= current(I) (in amps)*voltage(V) (in volts)
  1. p=i*v
forces
1. an object will not change velocity unless theres an unbalenced force
2. force (N)= mass(M)(in KG)*acceleration (A) (in m/s2)
3. force=(mv-mu)/time taken
momentum
1. momentum(kg in m/s)=mass (m in kg)*velocity (in m/s)
2. collisions
  1. momentum change: force*time= increase in acceleration
  2. elastic collisions: colliisions where no kinetic energy is lost by transformed into other energy types
  3. momentum before=momentum after
  4. newtons law of motion
    1. things dont speed up or slow down or change direction unless you push or pull them
    2. when you push something it pushes back just as hard but in the oppisite direction
acceleration
1. acceleration=change in speed/time taken
2. rate at which an object changes speed
moments
1. moment of force (Nm)=force (N)*perpendicular distance from pivot (d)(in m)
2. an object will be in balence if sum of antilclockwise moments=sum of clock wise moments
types of orbit
1. low polar orbit
  1. weather
    1. spying
      1. observing earths surface
2. geo stationary statellites
  1. stationed over equator
  2. doesnt move
  3. communtications
    1. gps
3. orbital speed: 2*3.142(pi)*orbital radius/time period
  1. 23.142r/t
light
1. reflection
  1. when a ray of light strikes a mirror it is reflected so that the angle of incidence is equal to the angle of reflection
  2. mirrors are used to change the direction of ray of light
  3. images are created from rays of light in mirror reflections
    1. virtual thing=images were light doesnt pass
    2. real images= images created with light passing through them
2. refraction
  1. light travels at 300,000,000m/s
  2. the change in speed may cause ray to change direction. this is refraction
  3. refractive index
    1. to find the angles of refrection
    2. n=sin i/sin r
  4. total internal reflection
    1. 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
    2. sin c=1/n
3. transverse waves can be feflected, refracted and diffracted
4. ray diagrams
magnetic fields
1. volume of space where magnetism can be detected
2. cannot be seen but with iron filings you can see it
3. when north and south poles are placed near each other there is an almost uniform field between the two poles
sound
1. sound waves
  1. as a speaker comes to the right it pushes air molecules together creating a compression
  2. this is a longitude sound wave and can be reflected, refracted and disfracted
2. speed of sound
  1. echoes
    1. divide distance by time
  2. resonance tube and tuning forks
  3. oscilloscope
3. reflected sound wave is called an echo
electromagnetic spectrum
1. visiable light
2. gamma radiation
  1. killing cancer cells
  2. shortest wave length
3. x rays
  1. medical images of bones
4. ultraviolet radiation
  1. sunbeds
5. visiable light
  1. seeing
6. infrared radiiation
  1. optical fibre radiation
7. microwaves
  1. cooking
8. radio waves
  1. tv signals
  2. longest wave length
energy transfers
1. we need to convert energy from place to place to be useful
2. energy becomes concerted an wasted
3. eg: heating water the engery converted is lost as its not doing what we want making the water hot
heat transfers
1. can be transferred by conduction, convention and radiation
  1. heat energy is transferred by conduction
  2. liquids and gases by convention
    1. 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.
  3. All objects give out and take in thermal radiation, which is also called infrared radiation.
radiation
1. plum pudding model
  1. J.J. thompson found negatively charged particles(electrons)
2. nuclear model
  1. alpha particles go straight through foil
  2. alpha particles werent deflected
  3. most the atom is an empty space
  4. most the mass is in the nucleus
  5. nucleus of an atom has a positive charge

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	Criado por daysi273 aproximadamente 9 anos atrás