materials

• What is the definition of tensile forces?

  They produce extension in an object.
• What happens to an object under tensile forces?

  It stretches and produces extension.
• What is the definition of compressive forces?

  They tend to reduce the length of a material.
• What does Hooke's Law state?

  Applied force is directly proportional to extension.
• What does 'f' represent in Hooke's Law?

  Applied force measured in newtons.
• How is extension calculated?

  Final length minus initial length.
• What is the spring constant often called?

  Force constant.
• What are the units of the spring constant \( k \)?

  Newtons per meter.
• What is the procedure to demonstrate Hooke's Law in an experiment?

  • Suspend masses from a spring.
  • Measure the extension.
  • Calculate force using \( f = mg \).
  • Plot a graph of force against extension.
• Why should readings be taken at eye level in the experiment?

  To reduce parallax error.
• What does a straight line through the origin in the graph indicate?

  Hooke's Law is valid for the material.
• What does the gradient of the force against extension graph represent?

  It equals the spring constant \( k \).
• What is the formula for the area under the force-extension graph?

  Area = \( \frac{1}{2} f x \).
• What does the area under the curve represent?

  Work done or elastic potential energy.
• What are the two formulas for elastic potential energy?

  \( \frac{1}{2} f x \) and \( \frac{1}{2} k x^2 \).
• What is stress defined as?

  Force applied divided by cross-sectional area.
• What are the units of stress?

  Newtons per meter squared or pascals.
• How is strain defined?

  Extension divided by original length.
• What is the symbol for strain?

  \( \epsilon \) (epsilon).
• Why is strain considered unitless?

  It is a ratio of lengths.
• What is ultimate tensile strength?

  Greatest stress before breaking point.
• What is Young's modulus defined as?

  Ratio of tensile stress to tensile strain.
• What is the formula for Young's modulus?

  \( E = \frac{\sigma}{\epsilon} \).
• What is the procedure to determine Young's modulus of a metal wire?

  • Clamp a wire with a pulley.
  • Attach varying masses to the wire.
  • Measure extension with a ruler.
  • Calculate stress and strain.
  • Plot force against extension graph.
• What is the purpose of using a micrometer screw gauge in the experiment?

  To determine the diameter of the wire.
• What is the formula for the cross-sectional area of a wire?

  \( A = \pi \left( \frac{d}{2} \right)^2 \).
• Why might a traveling microscope be used in the experiment?

  To measure small extensions accurately.
• What does the graph of force against extension indicate about Young's modulus?

  Gradient equals Young's modulus times area over length.
• What is a ductile material?

  Material that can be drawn into wires.
• What is elastic deformation?

  Material returns to original shape after force removal.
• What is plastic deformation?

  Material does not return to original shape after force removal.
• What are the key points in the stress-strain graph for ductile materials?

  • Stress is proportional to strain up to limit of proportionality (point P).
  • Elastic limit (point E) indicates start of permanent deformation.
  • Ultimate tensile strength is the maximum stress before breaking.
  • Breaking point is where the material fails.
• What are the characteristics of stress-strain graphs for brittle materials?

  • Straight line through origin to breaking point.
  • Stress is proportional to strain until breaking point.
  • Elastic deformation occurs until breaking point.
• What are the characteristics of stress-strain graphs for polymeric materials?

  • Distinctive shape under tensile and compressive stress.
  • Elastic behavior: returns to original shape after force removal.
  • Hooke's law is not obeyed; energy loss occurs.
• What happens to polythene under stress?

  Initially obeys Hooke's law, then exhibits plastic behavior.
• What is the significance of energy loss in polymeric materials?

  Energy is often lost as heat.
• What should you do if you have questions after the lesson?

  Drop a comment down below.
• What should you do if you found the video useful?

  Give it a like and subscribe.
• What is the final message of the lesson?

  Thank you for watching and see you soon.
• What is the purpose of the g-clamp in the experiment?

  To safely clamp the spring in place