science f2 chap8

• Force


  A pull or a push upon an object
• Force


  • A vector quantity that has magnitude and direction
• Newton


  S.I. unit for force
• Newton's Third Law


  For every action force, there is a reaction force of the same magnitude but in the opposite direction
• Types of forces


  • Gravitational force
  • Normal force
  • Weight
  • Buoyant force
  • Frictional force
  • Elastic force
• Effects of force


  • Change shape, size and motion of the object
• Buoyant force


  Actual weight - Apparent weight
• The denser the object


  The lesser the buoyant force than the object. Thus, the object submerge
• The less dense the object

  The higher the buoyant force than the object. Thus, the object float
• Lever


  A bar that rotates on a fixed point
• Parts of a lever

  • Effort - Force applied on the bar
  • Load - Object to be moved
  • Fulcrum - Fixed support point
• Classification of levers


  • First class lever
  • Second class lever
  • Third class lever
• Fulcrum in first class lever

  Between load and effort
• Load in second class lever

  Between fulcrum and effort
• Effort in third class lever

  Between fulcrum and load
• Moment of force


  Turning effect produced by a force acting on an object at a fixed point
• Pressure


  Force per unit area (direction of force is perpendicular to the surface area)
• Gas pressure


  The force produced by the collision of air molecules with the walls of the container
• Factors that affect gas pressure

  • Volume
  • Temperature
  • Atmospheric Pressure
• Atmospheric pressure


  The pressure exerted by the atmosphere on the surface of the Earth and all objects on the Earth
• Altitude increases


  Atmospheric pressure decreases
• Depth increases


  Liquid pressure increases
• Effects of depth on liquid pressure

  • Walls of a dam are thicker at the base to withstand high water pressure
  • Divers wear special suits to withstand high water pressure