This document defines key terms related to Young's modulus including: - Stress is the force applied per cross-sectional area of a material. - Strain is the extension in length resulting from stress. - Brittle materials break without plastic deformation. - Elastic materials return to their original shape after deformation. It also provides examples of materials that exhibit properties such as being stiff, elastic, plastic, ductile, malleable, strong, brittle, tough, smooth, and durable. The document outlines measurements needed to calculate stress and strain and discusses working out uncertainty when multiplying or dividing units.

1. Young’s
Modulus

2. Define the following
• Strain
• Stress
• Brittle
• Elastic

3. Define the following
• Stress – The force applied per cross-sectional area of a
material
• Strain – The extension in length resulting from stress
• Brittle – A material that breaks without plastic
deformation
• Elastic – A material that returns to its original shape
after deformation

4. Define the following
Key Word Definition Example
Stiff Does not easily change shape when force is applied Glass
Elastic Returns to original shape when force is removed. Copper
Plastic Remains deformed when force is removed Blu-tac
Ductile Can be readily pulled out into a thinner shape. Copper
Malleable Can be deformed under compression Copper
Strong Requires a large force to break it Steel
Brittle Easily cracks Glass
Tough Needs a large force to deform it Kevlar
Smooth Low friction surface PTFE
Properties do not deteriorate with repeated loading
Durable Bone
and unloading

5. Stress vs Strain

7. Things we will need to measure to
start

8. The Table
Mass (kg) Weight (N) Area (m2) Stress Length (m) Extension Strain
(N/m2) (m)

9. Working out uncertainty

10. Working out uncertainty 2
• Whether you are multiplying or dividing units,
you will always add the uncertainties together.
• I measure the side of a cube to be 10±0.5cm
• What is its volume if all dimensions are the
same?
• What is the uncertainty with that volume?