1. Young’s Modulus - an extension to Hooke’s Law Main Questions: –Why are mechanical properties important for engineers? –How is Young’s modulus related to Hooke’s Law? –How do scientists test materials to calculate the Young’s modulus? –What is the difference between materials with high Young’s modulus vs. materials with a low value? Duration: 3-5 days

2. Amazing footage on of it here.here

3. The main causes of engineering disasters are: human factors (including both 'ethical' failures and accidents) design flaws materials failures extreme conditions or environments and, of course, any combination of any of these

5. Mechanical Properties numerical value used to compare benefits of one material vs. another specific units serves to aid in material selection

7. Hooke’s Law The amount of force applied is proportional to the amount of displacement (length of stretch or compression). –The stronger the force applied, the greater the displacement is. –Less force applied, the smaller the displacement of the spring.

8.  F - applied force  k – spring constant  x - amount of displacement  k = 60 N/m 60 N will produce a displacement of 1 m  What force will make the spring stretch a distance of 5 m?  Which spring will have a greater spring constant, aluminium spring, or steel spring? Why? Hooke's Law applies to all solids: wood, bones, foam, metals, plastics, etc...

9. Young’s modulus Measures resistance of material to change its shape when a force is applied to it Related to atomic bonding Stiff - high Young's modulus Flexible - low Young's modulus Young’s Modulus (x10 9 Pa) cotton5 leather0.22 brass110 copper130 lead14 nylon1.8 Brick28 Concrete24 Diamond11,000 Pine13, 1.2 natural rubber 0.0019

10. Same as Hooke’s Law – the stretching of a spring is proportional to the applied force F = -k x σ = Ε ε Young’s Modulus (modulus of elasticity)

11. Young modulus is large for a stiff material – slope of graph is steep Is a property of the material, independent of weight and shape Units are usually GPa (x10 9 Pa) Stress vs. strain graphs

12. How do scientists calculate Young’s Modulus??? http://www.msm.cam.ac.uk/doitpoms/tlplib/thermal-expansion/simulation.php