1.4 - Materials

Use density ρ = m/V.

Use - density to connect the rule to the data and decision in the question.

This matters because - density determines what can be inferred or chosen; begin with the stated conditions and keep the conclusion tied to the evidence.

Example: apply - density to one small, clearly defined case, show the key step or comparison, and explain the result in words.

Boundary: - Density is not a universal recommendation. Check the syllabus scope, assumptions, units and the limits of the evidence before generalising.

Understand how to use the relationship upthrust = weight of fluid displaced.

Use - upthrust and displaced fluid to connect the rule to the data and decision in the question.

This matters because - upthrust and displaced fluid determines what can be inferred or chosen; begin with the stated conditions and keep the conclusion tied to the evidence.

Example: apply - upthrust and displaced fluid to one small, clearly defined case, show the key step or comparison, and explain the result in words.

Boundary: - Upthrust and displaced fluid is not a universal recommendation. Check the syllabus scope, assumptions, units and the limits of the evidence before generalising.

A be able to use the equation for viscous drag (Stokes’ Law), F = 6πηrv. b understand that this equation applies only to small spherical objects moving at low speeds with laminar flow (or in the absence of turbulent flow) and that viscosity is temperature dependent.

Use - stokes’ law and viscosity to connect the rule to the data and decision in the question.

This matters because - stokes’ law and viscosity determines what can be inferred or chosen; begin with the stated conditions and keep the conclusion tied to the evidence.

Example: apply - stokes’ law and viscosity to one small, clearly defined case, show the key step or comparison, and explain the result in words.

Boundary: - Stokes’ law and viscosity is not a universal recommendation. Check the syllabus scope, assumptions, units and the limits of the evidence before generalising.

CORE PRACTICAL 2: Use a falling-ball method to determine the viscosity of a liquid.

Use - core practical 2 - viscosity by falling-ball method to connect the rule to the data and decision in the question.

This matters because - core practical 2 - viscosity by falling-ball method determines what can be inferred or chosen; begin with the stated conditions and keep the conclusion tied to the evidence.

Example: apply - core practical 2 - viscosity by falling-ball method to one small, clearly defined case, show the key step or comparison, and explain the result in words.

Boundary: - Core Practical 2 - viscosity by falling-ball method is not a universal recommendation. Check the syllabus scope, assumptions, units and the limits of the evidence before generalising.

Be able to use the Hooke’s law equation, ∆F = k∆x, where k is the stiffness of the object.

Use - hooke’s law to connect the rule to the data and decision in the question.

This matters because - hooke’s law determines what can be inferred or chosen; begin with the stated conditions and keep the conclusion tied to the evidence.

Example: apply - hooke’s law to one small, clearly defined case, show the key step or comparison, and explain the result in words.

Boundary: - Hooke’s law is not a universal recommendation. Check the syllabus scope, assumptions, units and the limits of the evidence before generalising.

Understand how to use the relationships (tensile or compressive) stress = force/cross-sectional area (tensile or compressive) strain= change in length/original length Young modulus = stress/strain.

Use - stress, strain and young modulus to connect the rule to the data and decision in the question.

This matters because - stress, strain and young modulus determines what can be inferred or chosen; begin with the stated conditions and keep the conclusion tied to the evidence.

Example: apply - stress, strain and young modulus to one small, clearly defined case, show the key step or comparison, and explain the result in words.

Boundary: - Stress, strain and Young modulus is not a universal recommendation. Check the syllabus scope, assumptions, units and the limits of the evidence before generalising.

A be able to draw and interpret force-extension and force-compression graphs b understand the terms limit of proportionality, elastic limit, yield point, elastic deformation and plastic deformation and be able to apply them to these graphs.

Use - force-extension and force-compression graphs to connect the rule to the data and decision in the question.

This matters because - force-extension and force-compression graphs determines what can be inferred or chosen; begin with the stated conditions and keep the conclusion tied to the evidence.

Example: apply - force-extension and force-compression graphs to one small, clearly defined case, show the key step or comparison, and explain the result in words.

Boundary: - Force-extension and force-compression graphs is not a universal recommendation. Check the syllabus scope, assumptions, units and the limits of the evidence before generalising.

Be able to draw and interpret tensile or compressive stress-strain graphs, and understand the term breaking stress.

Use - stress-strain graphs and breaking stress to connect the rule to the data and decision in the question.

This matters because - stress-strain graphs and breaking stress determines what can be inferred or chosen; begin with the stated conditions and keep the conclusion tied to the evidence.

Example: apply - stress-strain graphs and breaking stress to one small, clearly defined case, show the key step or comparison, and explain the result in words.

Boundary: - Stress-strain graphs and breaking stress is not a universal recommendation. Check the syllabus scope, assumptions, units and the limits of the evidence before generalising.

CORE PRACTICAL 3: Determine the Young modulus of a material.

Use - core practical 3 - young modulus to connect the rule to the data and decision in the question.

This matters because - core practical 3 - young modulus determines what can be inferred or chosen; begin with the stated conditions and keep the conclusion tied to the evidence.

Example: apply - core practical 3 - young modulus to one small, clearly defined case, show the key step or comparison, and explain the result in words.

Boundary: - Core Practical 3 - Young modulus is not a universal recommendation. Check the syllabus scope, assumptions, units and the limits of the evidence before generalising.

Calculate elastic strain energy using ΔEel = ½FΔx and the area under a force–extension graph, including estimating areas for linear and non-linear graphs.

Use - elastic strain energy to connect the rule to the data and decision in the question.

This matters because - elastic strain energy determines what can be inferred or chosen; begin with the stated conditions and keep the conclusion tied to the evidence.

Example: apply - elastic strain energy to one small, clearly defined case, show the key step or comparison, and explain the result in words.

Boundary: - Elastic strain energy is not a universal recommendation. Check the syllabus scope, assumptions, units and the limits of the evidence before generalising.