Physics- key stuff


Distance- time graphs

  • The steeper the gradient, the faster the speed.
  • ---------------------------------------------------
  • Straight line= constant speed.
  • --------------------------------------------------
  • Flat horizontal= standing still
  • -------------------------------------------------
  • Curved = acceleration
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Velocity graphs

  • Straight line= acceleration


  • Flat horrizontal= constant speed


  • Distance travelled = area under graph
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  • Units for force: N
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mom= m x v

  • Momentum is a vector.
  • -------------------------------------------------------------
  • Unit for momentum= kgm/s



Mom before = mom after

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Stopping Distance

Reaction time: how long it takes to see someting, process it, and react.

Thinking distance:the distance moved (in car) when you are processing something (dog in road).

Breaking distance: the distance travelled once you have hit the breaks.

stopping distance= thinking + breaking

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Factors affecting stopping distance stuff

Factors affecting reaction time:

  • drugs
  • tiredness
  • age
  • drunkness

Factors affecting breaking distance:

  • condition of car
  • condition of road
  • massof car
  • speed of car
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Hooke's Law- Extention

Extention= new length - orginal length

  • force= mass x gravity
  • gravity= 10
  • curve on top of line graph is the elastic limit!

spring constant= Force / extention



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Terminal velocity

Terminal velocity:

  • 0 resulutant force
  • 0 acceleration
  • costant speed

Faster= more air resistance

  • Eventually, all energy is used up to overcome air resistance. 
  • =forces are balanced when object is falling.
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Work done= force x distance moved

Units for energy: joules

Power = work done / time taken

 1 watt = 1J / 1s

                    EP= m x g x h   Gravitational potential

           EK= 1/2 mv    Kinetic

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Moment- turning effect of a force (pivot)

moment of force= force x perpendicular distance from pivot

  • Moments have a direction
  • .
  • Centre of mass:   point where an object's mass is

.thought to act through

  • wide base = more stable
  • lower centre of mass = more stable
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Circular motion + pressure

Circular motion:

  • Velocity has a direction, as is changeing. If velocity changes, there must be an accelaration. Therefore, an object going at the same speed can be accelerating (in a circle)
  • Centripetial force: force acting towards centre of mass.
  • .


pressure= force / area


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Convex/ converging: forms a real image.

Concave/ diverging: forms a virtual image.

Lense Formula:  1   +     1  =      1                                u          v         f

Magnification:  image height                                        object height

Power of Lense:       1                                                 focal length


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The eye

 Short sight: light focuses too quickly. Only see close objects                             clearly.

correction: diverging lense.

 Long sight: light focuses behind retina. Only distant objects                             clearly.

correction: converging lense.

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Electric current

If an object looses electons it becomes positive

If an object gains electrons it becomes negative.

Ion: a charged atom

Electric current: a flow of charge. Measured by an ammeter. AMPS

Battery: two or more cells connected together.

current=  charge flow                                                                 time taken

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Potential Difference

 Potential Difference:                   Voltage = potential difference

A mearure of energy transferreent across a component

Meassured by volt meter. VOLTS.

potential difference=  energy transferred                                                       charge

 Resistance: ions resit the passage of electrons

Measured in : ohms

resistance= potential difference  Larger resistance= smallercurrent                    current

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