Mechanics + Materials

• What is Young's modulus a measure of?

  Stiffness of a material
• What does the gradient of a stress-strain graph represent?

  Young's modulus
• What does the area under a stress-strain graph represent?

  Strain energy per unit volume
• How is Young's modulus calculated?

  Stress divided by strain
• What is the formula for energy per unit volume?

  Energy per unit volume = ½ x Stress x Strain
• What does Hooke's Law state?

  Force is directly proportional to extension

  
• What is tensile stress?

  Force applied per unit area
• What is tensile strain?

  Extension per unit original length
• What is breaking stress?

  Stress at which a material fractures
• What is ultimate tensile stress?

  Maximum stress a material can withstand
• How does a brittle material behave under stress?

  Fractures without plastic behavior
• How does a ductile material behave under stress?

  Can be stretched into long wires
• What is the elastic limit?

  Maximum stress without permanent deformation
• What is elastic deformation?

  Material returns to original shape
• What is plastic deformation?

  Material is permanently stretched
• What is the formula for work done in terms of force and extension?

  Work Done = ½ F ΔL
• What is the relationship between work done and energy stored?

  Work done equals energy stored
• What is the formula for kinetic energy?

  Ek = ½ m v²
• What happens in an inelastic collision?

  Kinetic energy is not conserved
• What happens in an elastic collision?

  Kinetic energy is conserved
• What is impulse?

  Change in momentum or force times time
• What does the area under a force-time graph represent?

  Impulse
• What is the formula for power?

  P = ΔW / Δt
• What is density?

  Mass per unit volume
• How is the density of a liquid measured?

  By measuring mass and volume
• How is the density of a solid measured?

  By measuring mass and water displacement
• What is drag?

  Force opposing motion in a fluid
• What is lift?

  Upward force on an object in a fluid
• What is terminal velocity?

  When frictional forces equal driving force
• What does SUVAT stand for?

  Displacement, Initial velocity, Final velocity, Acceleration, Time
• How are horizontal and vertical components treated in projectile motion?

  They are treated separately
• What is Newton's first law?

  Velocity changes only if a resultant force acts
• What is Newton's second law?

  f = ma (force equals mass times acceleration)
• What is Newton's third law?

  Every force has an equal and opposite force
• What is the centre of mass?

  Point where mass is concentrated
• How can the centre of mass be found?

  By suspending an object and using a plumb line
• What happens if the line of action falls outside the base?

  The object will topple
• What is the difference between vectors and scalars?

  Vectors have magnitude and direction
• How can vectors be represented visually?

  With arrow drawings
• What does resolving a vector mean?

  Splitting it into horizontal and vertical components