Resolving forces and equilibrium

• Types of forces


  Weight

  Friction

  Normal reaction

  Tension

  Thrust
• What is weight in terms of gravitational force?

  Gravitational force between a mass and Earth
• What is the formula for weight?

  Weight = mg
• What does 'm' represent in the weight formula?

  Mass in kilograms
• What does 'g' represent in the weight formula?

  Acceleration due to gravity, 9.8 m/s²
• In which direction does weight act?

  Vertically down from the centre of mass
• What is friction?

  A force that opposes motion
• What does the size of friction depend on?

  Roughness of surfaces in contact
• What is the normal reaction force?

  Force between a body and a surface
• In which direction does the normal reaction act?

  Perpendicular to the surface
• What is tension in a string?

  Resistive force that opposes stretching
• What is thrust?

  Resistive force provided by a spring or rod
• What are modelling assumptions in physics?

  Simplifications made to describe systems
• What is assumed about strings in modelling?

  They are light and inextensible
• What does it mean for a string to be inextensible?

  It does not stretch, tension remains constant
• How are objects/masses treated in modelling?

  As particles with negligible dimensions
• What is assumed about rods in modelling?

  They are uniform along their length
• Where is the centre of mass of a rod assumed to be?

  At the centre of the rod