Physics paper one

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Forces

Vector and Scaler Quantities

  •  A scaler quanitiy has magnitude (size) only i.e the number of fish.
  • A vector quantity has magnitude and direction i.e velocity, which shows the speed and direction of travel
  • Arrows can be used to show vector quantities- the length of the arrown represents the magnitude and the direction of the arrow shows where the vector is acting 
  • Forces are vector quantites

Contact and Non Contact Forces

Force is applied when two objects tough wach other.

  • Forces are either - contact- where the forces actually tough each other i.e. two people pulling one another or friction.
  • Non contact- where objects do not touch directly i.e gravity  and magnetic force

Resultant Forces -When more than one force acts on an object, these forces can be seen as a single force that has the same effect as all the forces acting together

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Forces

Gravity

  • Gracvty is a force acting in all objects  due to the gravitational field around earth
  • A mass of an object is related to the amount of matter it contains and is constant
  • Weight is the force acting on an object due to gravity an object is directly proportional to its mass as weight depends on the gravitational field strength
  • Weight = mass X Gravitational Field Strength

Vector Diagrams (Higher Tier)

  •  A free body diagram can be used to show different forces acting on an object  and scale vector diagrams cn be used to show the overall effect when mor ethan one firce is applied. 
  • The forces are added together to find a resultant firce including bothe magnitude and directon. when the vectors are added head to tail and a rsultant arrow is drawn.
  • Scale vector diagrams can be used when a force is acting in a diagonal direction.
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Forces

Work done and Energy Transfer

  • When a force is added to an object cause its to move, work is done because it requires energy to move.
  • one joule of work is done when a force of one newton cause the displacement of one metre 1 joule = 1 newton metre
  • Work Done = Force X Distnace  
  • When work is done then energy is transfers takes place in the system 

Pressure in a System

  • A fluid can be liquid or gas as particles move round the fluid they collide with the surface of the objects or the container surface. the collision creates a force normals(at right angles) to the surface
  •  Pressure = Force normal to a surface  ÷  Area of that surface
  • If the presssure acts on a bigger surafce area then its will create a larger force
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Forces

Forces and elasticity

  • For an object to change its shape then more than one force must be applied.
  • If the object returns to origonal shape after the forces are removed then it is elastically deformed if it doesnt change bavk to normal then its inelasticly deformed
  • The extension of an object is directily proprtional to the applied force 
  • However once the limit of proprtionality has been reached then doubling the force will no longer double the extensio, the relationship becomes non-linear, a force-extension graph will no longer be a straight line.
  • Force = Spring constand X Extension 
  • It also applies to the compression of an elastic object. the spring constant shows how the easy it is ti strecth or comprress the spring ( the higher the spring constant the stiffer the spring)
  • A force that stretches or compresses a string stores elastic potential energy in the  stpring.
  • The amount of work done is equal to the energy stroed as long as the spring doesnt go past its limit of proportionality
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Forces

Moments, Levers, and Gears.

  • When a force is applied to an object and causes it to rotate abouyt a pivot point the turning effect is called moment of a force.
  • Moment of a force =Force X Distance
  • If an object is balamced then the total clockwise rotation is equal to the total antuclockwise moment around the pivot.
  • Levers and Gears are used to  transmit the rotationl effects of forces, and magnify either the size of applied force or the distance the force moves over.
  • When the applied force moves further than the transmitetd force then the force is increase.

Speed

  • Speed is a scalar quantitu ,easued in metres per sevomd  most things (like sound) don not tarvel at a constant sepeed so it is ofetn the average soeef=d over a period of time that is used 
  • Distance travelled = Speed X Velocity
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Forces

Atmospheric Pressure 

  • The greater the altitude the less dense the atmosphere and the lower the atmospheric pressure. At a high altitide there is less air above the surface than at lower altidues she there is a smaller weight of air acting on the surface.

Pressure in a column of liquid (Higher Tier)

  • Pressure at a particular point in a column depends on the height of the column above the point and the density of the liquid.
  • The higher the column the more dense the liquid the greater the weight above the point the greater the force in the surface at that point the greater the pressure.
  • Pressure = Height of column X Density of liquid X Gravitational Field Strength 
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Forces

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