Free Body Diagrams & Resultant Forces

• What are free body diagrams used for?


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

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

  Using force arrows
• In a free body diagram of a plane, what does the forward arrow represent?

  Thrust
• What does the downward arrow in a free body diagram represent?

  Weight
• Why do we label forces in newtons?

  To indicate the magnitude of the force
• What happens to forces acting in different directions in a free body diagram?

  Some forces cancel each other out
• How do you calculate the resultant force in vertical components?

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

  Zero newtons overall
• What is the resultant force if there are 120,000 newtons to the right and 90,000 newtons to the left?

  30,000 newtons to the right
• What does it mean if both horizontal and vertical components are balanced?

  The object is in equilibrium
• What happens if air resistance is 120,000 newtons in the horizontal component?

  The horizontal resultant force would be zero
• What is the overall resultant force when both components are balanced?

  No resultant force acting on it
• What are the steps to find the resultant force using free body diagrams?

  1. Identify all forces acting on the object
  2. Draw arrows to represent each force
  3. Label the forces in newtons
  4. Calculate vertical and horizontal components separately
  5. Subtract opposing forces to find resultant force
  6. Determine if the object is in equilibrium