Forces

• What do scalar quantities have?

  Magnitude only
• Give an example of a scalar quantity.

  Speed
• What do vector quantities have?

  Magnitude and assigned direction
• Give an example of a vector quantity.

  Force
• How is a vector quantity represented?

  By an arrow indicating magnitude and direction
• What is a force?

  A push or pull acting on an object
• What are contact forces?

  Forces when objects are physically touching
• Give an example of a contact force.

  Friction
• What are non-contact forces?

  Forces when objects are physically separated
• Give an example of a non-contact force.

  Gravitational force
• What happens when two objects interact?

  A force is produced on both objects
• What is the interaction pair of forces?

  Equal and opposite forces acting on two objects
• What does gravity do?

  Attracts all masses
• What effect does gravity have on objects on a planet's surface?

  It makes all things fall towards the ground
• What is weight?

  The force acting on an object due to gravity
• How is weight calculated?

  Weight (N) = mass (kg) x gravitational field strength (N/kg)
• What does the weight of an object depend on?

  The gravitational field strength at its location
• How is weight measured?

  Using a newtonmeter
• What is resultant force?

  • A single force replacing multiple forces
  • Has the same effect as all original forces
  • Found by adding forces in the same direction and subtracting those in the opposite direction
• What do free body diagrams show?

  All forces acting on an object
• What indicates an object is in equilibrium?

  Balanced forces with resultant force zero
• How can a single force be split?

  Into two components acting at right angles
• What happens when a force moves an object through a distance?

  Energy is transferred and work is done
• What is the formula for work done?

  Work done (J) = force (N) x distance (m)
• What is 1 Joule equivalent to?

  1 newton metre
• What happens when work is done against frictional forces?

  It causes a rise in temperature of the objects
• What is the turning effect of a force called?

  Moment
• What is the formula for the moment of a force?

  Moment of force (Nm) = Force (N) x Distance (m)
• How can you achieve maximum moment?

  Push at right angles to the lever
• How do gears transmit force?

  By interlocking teeth that turn in opposite directions
• What do levers do?

  Make it easier to do work
• What happens when a force is transmitted to a larger gear?

  It causes a bigger moment
• What happens to the larger gear's speed compared to the smaller gear?

  The larger gear will turn slower
• What happens when a force stretches or compresses an object?

  It may strengthen, compress, or bend the object
• What is elastic deformation?

  When an object returns to its original shape
• What is inelastic deformation?

  When an object does not return to its original shape
• What happens to energy when an object is elastically deformed?

  Energy is transferred to the elastic potential energy store
• What is the formula for elastic potential energy?

  Elastic potential energy (J) = 0.5 x spring constant (N/m) x extension (m)
• What happens when a spring is stretched?

  Extension is directly proportional to the force applied
• What does the spring constant depend on?

  The material being stretched