Resultant Forces & Free Body Diagrams

• What are free body diagrams used for?

  To find the resultant force on an object
• What do free body diagrams represent?

  All forces acting on a particular object
• How do we represent forces in free body diagrams?

  Using force arrows
• What does the length of the arrows in a free body diagram indicate?

  The magnitude of the force
• What are the four forces acting on a plane in the example given?

  Thrust, drag, weight, lift
• Why do some forces cancel each other out in free body diagrams?

  Because they act in opposite directions
• How do you calculate the resultant force in vertical components?

  By subtracting opposing forces
• What is the resultant force when there are 80,000 newtons up and 80,000 newtons down?

  Zero newtons overall
• What is the resultant force in the horizontal component with 120,000 newtons right and 90,000 newtons left?

  30,000 newtons to the right
• What happens to the resultant force if air resistance is 120,000 newtons?

  The horizontal resultant force becomes zero
• What does it mean if both horizontal and vertical components are balanced?

  The object is in equilibrium
• What are the steps to find the resultant force using free body diagrams?

  1. Identify all forces acting on the object.
  2. Represent each force with arrows.
  3. Determine the magnitude and direction of each force.
  4. Calculate the resultant force by considering horizontal and vertical components separately.
  5. Analyze if the object is in equilibrium or not.
• What are the key components of a free body diagram for a plane?

  • Thrust (forward)
  • Drag (backward)
  • Weight (downward)
  • Lift (upward)