Forces

• What is a scalar quantity?

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


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

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

  As an arrow
• 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?

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

  Contact forces and non-contact forces
• Is force a vector or a scalar quantity?

  Vector
• What does it mean for force to be a vector quantity?

  It has both magnitude and direction
• What is weight?

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

  The object's mass and gravitational field strength
• What is the formula for weight?

  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 weight acts through
• What is the name of the single force equivalent to all other forces acting on an object?

  The resultant force
• What equipment can measure an object's weight?

  A calibrated spring-balance or newton-meter
• What does it mean if a force is said to do ‘work’?

  The force caused and object to be displaced through a distance
• Explain the relationship between the force applied and the extension of an elastic object.

  The extension is directly proportional to the force applied, provided that the limit of proportionality is not exceeded. Known as Hooke law
• What is meant by an in elastic deformation?

  • A deformation which results in the object being permanently stretched
  • The object doesn't return to its original shape when the force is removed
• What type of energy is stored in a spring when it’s stretched ?

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

  A moment
• What distance measurement is used when calculating a moment?

  The perpendicular distance from the pivot
• If an object is in equilibrium, what can be said about the moments acting on it?

  The clockwise moments equal the anticlockwise moments
• What three parts make up a lever system?

  • Load
  • Effort
  • Pivot
• How can a lever be used as a force multiplier?

  Distance between effort and pivot is greater
• What determines the moment of a gear wheel?

  The size of the wheel
• Describe the moment and speed of a larger gear driven by a smaller gear.

  The larger wheel rotates slowly but produces a larger moment
• What is meant by the term ‘fluid’?

  A liquid or a gas
• At what angle do the forces due to pressure act on a surface in a fluid?

  At right angles (normal to) the surface
• What is the equation used to calculate pressure?

  Pressure = Force/Area
• What are the units for pressure, force, and area?

  Pressure (Pascals), Force (Newtons), Area (metre²)
• What happens to the density of the atmosphere with increasing altitude?

  The atmosphere becomes less dense as altitude increases
• Why does atmospheric pressure decrease with an increase in height?

  Fewer air molecules lead to lower pressure
• What creates atmospheric pressure?

  • Collisions of air molecules
  • Quantity of molecules decreases with height
  • Weight of air decreases with height
• What is the Earth’s atmosphere?

  A thin layer of gas surrounding the Earth
• How does pressure in fluids increase with depth?

  More liquid above increases the force
• Why does pressure in fluids increase with density?

  Higher density means more particles in volume