2.5. Materials

• Strength is the material's ability to withstand stress
• Hooke's Law states that the force required to extend a spring is proportional to the change in length
• Stress is measured in units of pascals
• What is the formula for Hooke's Law relating stress and strain?

  $\sigma =$$E\epsilon$
• A material with a high Young's Modulus is more flexible than one with a low Young's Modulus.

  False
• Elastic deformation results in permanent changes to the material's shape.

  False
• Why is Hooke's Law important in engineering design?

  Predicts material behavior
• What does yield strength indicate about a material?

  Ability to retain shape
• What does Hooke's Law describe in the context of elastic deformation?

  Force is proportional to change in length
• Temperature can alter the mechanical properties of a material.


  True
• Elasticity is the ability of a material to deform permanently without fracture.

  False
• What does thermal expansion measure in a material?

  Change in size with temperature
• What does Hooke's Law state about the relationship between force and length change in a spring?

  They are proportional within elastic limit
• Strain is a dimensionless quantity

  True
• Match the material property with its description:

  Strength ↔️ Ability to withstand stress without breaking

  Hardness ↔️ Resistance to surface scratching

  Elasticity ↔️ Returns to original shape after deformation

  Plasticity ↔️ Permanent deformation without fracture
• What does stress measure in a material?

  Force per unit area
• Stress is measured in units of pascals
• Young's Modulus is a measure of a material's stiffness
• Match the material property with its description:

  Strength ↔️ Ability to withstand stress

  Hardness ↔️ Resistance to scratching

  Elasticity ↔️ Return to original shape

  Plasticity ↔️ Permanent deformation
• The Young's Modulus is a measure of the material's stiffness
• Match the Young's Modulus property with its description:

  High Young's Modulus ↔️ High stiffness, small deformation

  Low Young's Modulus ↔️ Low stiffness, large deformation
• Ultimate tensile strength marks the onset of plastic deformation.

  False
• Match the deformation type with its property:

  Elastic Deformation ↔️ Returns to original shape

  Plastic Deformation ↔️ Permanently deformed
• Strength is the material's ability to withstand stress without breaking
• Hardness is a material's resistance to surface scratching or indentation
• Density is defined as mass per unit volume
• Elastic deformation results in permanent changes to a material's shape

  False
• What is the unit of measurement for stress?

  Pascals
• Match the property with its description:

  Elastic Deformation ↔️ Returns to original shape

  Plastic Deformation ↔️ Permanently deformed
• What is ultimate tensile strength?

  Maximum stress before fracture
• What are three factors that affect material properties?

  Composition, temperature, surface treatment
• Ceramics are used as insulators in electronics due to their high electrical resistivity.
• What are materials used for?

  Constructing objects or structures
• Arrange the following properties to distinguish between elastic and plastic deformation:

  1️⃣ Recoverability: Returns to original shape || Permanently deformed

  2️⃣ Material Behavior: Hooke's Law applies || Hooke's Law does not apply

  3️⃣ Example: Stretching a rubber band || Bending metal beyond its elastic limit
• Where does Hooke's Law apply in real-world scenarios?

  Suspension systems and elastic bands
• Hooke's Law applies to all types of materials regardless of stress levels.

  False
• What is the formula for calculating Young's Modulus?

  $E =$$\frac{\sigma}{\epsilon}$
• What is the formula for Hooke's Law relating force and extension in a spring?

  $F =$$k\Delta x$
• In elastic deformation, a material permanently changes its shape.

  False
• Ultimate tensile strength is the maximum stress a material can withstand before it starts to break