A-Level Physics – Properties of Materials
Core Ideas
- Materials deform when forces act – behavior depends on structure and bonding.
- Key relationships: force–extension, stress–strain, and energy storage.
- Used to determine stiffness, strength, and ductility of solids.
Density
𝑚
𝜌 =
𝑉
- Measure of mass per unit volume (kg m⁻³).
- Low ρ → light material (aerogel, air);
- High ρ → dense (steel, lead).
Hooke’s Law
𝐹 = 𝑘𝛥𝑙
- Extension proportional to force within elastic limit.
- k: spring constant (N m⁻¹).
- Elastic limit = maximum reversible deformation.
Elastic strain energy
𝐸 = 𝐹𝛥𝑙 = 𝑘𝛥𝑙²
Stress, Strain & Young Modulus
Stress (Pascals)
𝐹
𝜎=
𝐴
Strain (No units)
Δ𝑙
𝜖=
𝑙
Core Ideas
- Materials deform when forces act – behavior depends on structure and bonding.
- Key relationships: force–extension, stress–strain, and energy storage.
- Used to determine stiffness, strength, and ductility of solids.
Density
𝑚
𝜌 =
𝑉
- Measure of mass per unit volume (kg m⁻³).
- Low ρ → light material (aerogel, air);
- High ρ → dense (steel, lead).
Hooke’s Law
𝐹 = 𝑘𝛥𝑙
- Extension proportional to force within elastic limit.
- k: spring constant (N m⁻¹).
- Elastic limit = maximum reversible deformation.
Elastic strain energy
𝐸 = 𝐹𝛥𝑙 = 𝑘𝛥𝑙²
Stress, Strain & Young Modulus
Stress (Pascals)
𝐹
𝜎=
𝐴
Strain (No units)
Δ𝑙
𝜖=
𝑙
