Forces

Cards (10)

  • Force:
    An interaction that causes an object to start moving or speed up, stop moving or slow down, change direction or change shape
  • Types of forces:
    • push
    • pull
    • twist
    • Contact forces require physical contact between surfaces
    • Non-contact forces does not require physical contact/touch
  • An object at rest stays at rest and an object in motion stays in motion with the same speed and in the same direction unless acted upon by an unbalanced force
  • Unbalanced forces are not equal and they cause the motion of an object to change
  • Reaction force and gravitational force are a balanced pair of forces
  • Fomula for pressure:
    Pressure = force/area
    N/m2 pascal (Pa)
    1N/m2 = 1Pa
    common: N/cm2
  • Larger area - lower pressure (E.g. large tyre - the large area makes the pressure lower, so the vehicle is less likely to sink into the mud)
    Smaller area - higher pressure (E.g. sharp knife - the force you put on a knife is more concentrated over a smaller area)
  • Friction is the force that opposes motion between any surfaces that are in contact
  • Four types of friction:
    • static - the friction between two still objects resting on the surface
    • sliding - solids
    • rolling
    • fluid - gas & liquids