forces

• What is a scalar quantity?

  A quantity that only has a magnitude
• Why is a scalar quantity not direction dependent?

  It only measures magnitude, not direction
• What is a vector quantity?

  A quantity that has both magnitude and direction
• How can a vector quantity be represented visually?

  As an arrow indicating magnitude and direction
• What does the length of a vector arrow represent?

  The magnitude of the vector quantity
• What does the direction of a vector arrow indicate?

  The associated direction of the vector quantity
• What is a force?

  A push or pull acting on an object
• What causes a force to act on an object?

  An interaction with another object
• What are the two categories of forces?

  Contact forces and non-contact forces
• What are contact forces?

  • Forces that occur when objects touch
  • Examples include:
  • Friction
  • Air resistance
  • Tension
• What are non-contact forces?

  • Forces that act at a distance
  • Examples include:
  • Gravitational forces
  • Electrostatic forces
  • Magnetic forces
• Is force a vector or a scalar quantity?

  Force is a vector quantity
• What is weight?

  The force acting on an object due to gravity
• What does weight depend on?

  Mass and gravitational field strength
• How is weight calculated?

  Weight = mass x gravitational field strength
• What is the unit used for weight?

  The Newton (N)
• What is the unit used for gravitational field strength?

  N/kg
• What is meant by an object’s centre of mass?

  The point where an object's weight acts through
• What equipment measures an object's weight?

  A calibrated spring-balance or newton-meter
• What is the resultant force?

  The single force equivalent to all acting forces
• What does it mean if a force is said to do ‘work’?

  The force causes an object to be displaced
• What is the equation used to calculate work done?

  Work done = Force x Distance
• What are the appropriate units for work done, force, and distance?

  Work done (Joules), Force (Newtons), Distance (metres)
• What distance must be used when calculating work done?

  Distance moved along the line of action
• Under what circumstance is 1 joule of work done?

  When a force of 1 Newton causes 1 metre displacement
• How many Newton-metres are equal to 1 joule of energy?

  1 Nm = 1 J
• How much work is done by a force of 10N over a distance of 5m?

  50 J
• What occurs when work is done against frictional forces?

  Temperature rises and kinetic energy converts to heat
• Why does air resistance slow down a projectile?

  Work is done against air resistance, converting energy to heat
• What is the relationship between the force applied and the extension of an elastic object?

  The extension is directly proportional to the force applied
• What must not be exceeded for the relationship between force and extension to hold?

  The limit of proportionality
• What is meant by inelastic (plastic) deformation?

  A deformation resulting in permanent stretching
• What happens to an object after inelastic deformation when the force is removed?

  The object doesn’t return to its original shape
• What is the equation relating force, spring constant, and extension?

  Force = Spring Constant x Extension
• What are the appropriate units for force, spring constant, and extension?

  Force (N), Spring Constant (N/m), Extension (m)
• What type of energy is stored in a spring when it is stretched?

  Elastic potential energy
• What can extension be replaced with in the equation for spring force?

  Compression
• What is an alternative name for the turning effect of a force?

  A moment
• What is the equation used to calculate the moment of a force?

  Moment = Force x Distance
• What are the appropriate units for moment, force, and distance?

  Moment (Nm), Force (N), Distance (m)