Forces

• What does a free body diagram show?

  The forces acting on an object in different directions
• What is a moment?

  The turning effect of a force acting on an object
• What are moments in physics?

  The turning effect of a force
• How do moments act in relation to a point?

  They act in clockwise or anticlockwise direction
• What is a pivot in the context of moments?

  A point around which something can rotate
• What is the formula to calculate the magnitude of a moment?

  Moment = force × distance
• In which units is the moment measured?

  Newton-metres (Nm)
• What does the distance in the moment formula represent?

  The perpendicular distance from the pivot
• If a force of 15 N is applied at a distance of 12 cm from the pivot, what is the moment?

  1.8 Nm
• How do you convert 12 cm into metres?

  12 cm = 0.12 m
• What is the moment when a force of 40 N is applied at a distance of 30 cm?

  12 Nm
• What is the first step in calculating the moment of a force?

  Convert distance into metres
• What are the key concepts related to moments, levers, and gears?

  • Moments are turning effects of forces
  • Levers use moments to gain advantage
  • Gears transmit turning forces in machines
• What is the relationship between force, distance, and moment?

  • Moment (M) = Force (F) × Distance (d)
  • Measured in Newton-metres (Nm)
  • Distance is the perpendicular distance from the pivot
• What is terminal velocity?

  The maximum speed of an object
• What happens to an object at terminal velocity?

  Forces are balanced, resulting in zero force
• What factors affect stopping distances?

  Speed, mass, road surface, reaction time
• What is the acceleration of an object falling freely near Earth's surface?

  About 9.8 m/s²
• What is air resistance?

  A force of friction when moving through air
• What happens to a skydiver’s weight as they fall?

  The weight remains constant as they fall
• How does air resistance change as a skydiver accelerates?

  Air resistance increases as speed increases
• What occurs when a skydiver reaches terminal velocity?

  Weight is balanced by air resistance
• What happens when a parachute opens?

  Air resistance increases, slowing the skydiver
• What is a velocity-time graph used for?

  To show speed changes over time
• What are the three stages of falling through a fluid?

  1. Accelerating downwards due to gravity
  2. Increasing air resistance as speed rises
  3. Reaching terminal velocity with balanced forces
• What does a resultant force of zero indicate for a falling object?

  The object is at terminal velocity
• What happens to the resultant force as an object accelerates through a fluid?

  It decreases as frictional forces increase
• What is the speed of a skydiver at terminal velocity?

  About 53 m/s
• What does the resultant force acting downwards indicate during the fall?

  It indicates the object is still accelerating
• How does the resultant force change from stages A to D in a velocity-time graph?

  It decreases until reaching zero at terminal velocity
• What is the definition of resultant force?

  The single force replacing all acting forces
• What does it mean when the resultant force is zero?

  The object is in equilibrium and not accelerating
• What is the effect of gravity on a falling object?

  It causes the object to accelerate downwards
• What is the relationship between speed and air resistance during a fall?

  Speed increases, air resistance also increases
• How does the velocity-time graph illustrate the stages of falling?

  It shows acceleration, constant speed, and terminal velocity
• What is the unit of force?

  Newton (N)
• What happens when a force acts on an object?

  The object may change shape or motion
• What is required for a stationary object to change shape?

  More than one force must act on it
• How does an archer change the shape of an arrow?

  By pulling it back against a bow
• What happens when a rubber band is stretched?

  Its ends are pulled apart