Lesson 3 - Forces and Vectors

• What are scalars in engineering?

  Quantities with magnitude only
• Give an example of a scalar.

  Distance travelled
• What are vectors in engineering?

  Quantities with magnitude and direction
• Give an example of a vector.

  Displacement
• What does the symbol 'S' represent in engineering?

  Distance travelled
• What is the unit for speed in engineering?

  meters per second (m/s)
• What does the symbol 'u' represent in engineering?

  Velocity
• What is the unit for velocity in engineering?

  meters per second (m/s)
• What is the resultant vector called?

  Displacement
• How is the magnitude of the resultant vector determined?

  By the length of the resultant line
• What does the direction of the force vector represent?

  The angle of any triangle
• What is the tension in the rope of the pendulum?

  90N
• What is the weight of the bob in the pendulum?

  19.6N
• How is the weight of the bob calculated?

  w = mg
• What is the mass of the bob in the pendulum?

  2kg
• How do you find the resultant force acting on the pendulum bob?

  By resolving the tension and weight
• What is the scale used in the vector diagram?

  1cm = 1m
• What is the purpose of using a protractor in vector diagrams?

  To find angles
• What is the first step in resolving vectors?

  Draw them to scale
• What is the vertical component of a force vector?

  Ey
• What is the horizontal component of a force vector?

  Ex
• How do you calculate the vertical component of a force?

  Fy = F sin θ
• How do you calculate the horizontal component of a force?

  Fx = F cos θ
• What is the formula for Pythagoras' theorem?

  R² = a² + b²
• How do you find the hypotenuse using Pythagoras' theorem?

  R = √(a² + b²)
• How do you find the angle of the resultant using trigonometry?

  θ = tan⁻¹(O/H)
• What is the resultant force when two forces are combined?

  It is the vector sum of forces
• What are the common mistakes with scale vector diagrams?

  • Incorrectly drawing vectors
  • Not using the correct scale
  • Miscalculating angles
• What is the correct method for drawing a scale force diagram?

  • Use the "top to tail" method
  • Ensure accurate lengths and angles
  • Check the scale for unit conversion
• What are the steps to resolve vectors to solve a problem?

  1. Number the forces
  2. Construct a table for components
  3. Draw total X and Y as a triangle
  4. Find the hypotenuse using Pythagoras
  5. Find the angle of the resultant