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6. which of these is a catergories/mechanisms of injury?

  • Fast pace implements
  • Whiplash
  • High velocity projectiles
  • Angular implements
  • Indirect implements

7. Which of these is Not a way in which a material can fail.

  • Combustion which is heating
  • In tension: which is pulling
  • In shear: which is sliding, or the tendency for one part of a solid to slide past another.
  • In compression: which is pushing.

8. Most mechanical properties can be determined by carrying out a simple tensile test

  • True
  • False

9. How can you test the mechanical properties of a material

  • A dumbbell shaped sample is gripped at both ends and stretched. The extension (how much it stretches) and the force is continuously monitored
  • Heat the material
  • Freeze the material and allowing it to cool
  • Electronic microscope

10. Stress can be determined as:

  • An injury attained during a fast pace environment
  • the change in length over the original length
  • the force per unit area (N/m2) or Pa
  • the amount of heat a material can withstand

11. A Newton is defined as the force which when applied to a mass of 2kg gives it an acceleration of 1m/s2.) 2kg=9.81N

  • False
  • True

12. Which of the following is incorrect

  • Strain is represented in a ratio which is unit length
  • Strain is measured in cm/mg
  • The stress at failure is known as the strength of the material.
  • Strain is the change in length over the original length

13. Which of these is not derived from young modules?

  • Stress is Strain
  • Strain is propertional to stress
  • The correct symbol for the Young
  • A steep/high slope and the material is said to be stiff and a low slope and the material is said to be complian

14. The maximum point the curve reaches indicates on the y axis the breaking stress (strength) or on the x axis the extensibility or breaking strain

  • True
  • False

15. The strength of a material is its ability to resist the application of forces without compressing

  • False
  • True

16. Which best describes Elasticity?

  • If a material is stretched and then, after the force is removed, it returns to its original length it is said to be elastic
  • The ability to return to a form after compression
  • A string which rebounds after tugging
  • Flexibility of molecules

17. This point where the material undergoes plastic deformation is said to be the elastic limit.

  • True
  • False

18. Which of these are Not a mechanical term

  • Inflation
  • Yielding point
  • Breaking point
  • Breaking energy
  • Initial modules

19. Work of fracture or toughness is a measure of the energy required to stretch a material. This has units of energy (J) per unit area (m) i.e. J/m

  • False
  • True

20. Which is true about resilence?

  • resilence equates toughness
  • material cannot break if melted first
  • If a material is stretched and then released the unloading curve is always below the loading curve: some of the energy is lost.
  • brittle material has high resilence