Forces

• Contact forces have to be touching for the force to act
• Non-Contact forces - do not need to be touching for the force to act
• Contact forces:

  • Friction
  • Air resistance
  • Tension
• Non-Contact forces:

  • Magnetic
  • Gravitational
  • Electrostatic
• Gravitational

  • Attracts all masses
  • Gives everything a weight
  • Makes things fall to the ground
• Mass

  • The amount of “stuff” in an object
  • Has the same value anywhere
  • Measured in kilograms
• Weight

  • The force acting on an object due to gravity
  • GFS varies with location
  • Weight is a force measured in newtons
  • Varies with GFS
• Weight = Mass x Gravitational field strength