Stress, Strain and Hooke's Law

Name: Stress, Strain and Hooke's Law
Author: StemPy Lab

Why is a steel wire stretched only a little by a load that makes a rubber band much longer? In this course we define stress and strain, we find the law of Hooke, we read the stress-strain curve of a metal and see what happens when it yields and breaks, and we use Young's modulus to find how much a wire stretches.

3 lessons, about 1 h 15 min3 simulations12 problems6 practice questionsPython in every lesson

Created by StemPy Lab

Course outline (3 lessons)

Lesson 1about 25 min
Elasticity, stress and strain
A body is elastic if it returns to its shape when the force is removed. Stress is the restoring force per unit area, $F/A$ , in pascal; strain is the fractional change of shape, with no unit. Stretching or squeezing gives longitudinal stress and strain, a sideways force gives shear, and a pressure from all sides gives a change of volume.
1 simulation2 practice questions1 Python program4 problems1 question set
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Lesson 2about 25 min
Hooke's law and the stress-strain curve
Hooke's law: within the elastic limit, stress is in proportion to strain. The stress-strain curve of a metal is straight up to the proportional limit, bends at the elastic limit and the yield point, rises to the ultimate strength and falls to the breaking point. Ductile metals have a long plastic region; brittle materials break soon after the elastic limit.
1 simulation2 practice questions1 Python program4 problems1 Python lab
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Lesson 3about 25 min
Young's modulus and the stretching of wires
Young's modulus is the ratio of longitudinal stress to longitudinal strain, $Y = \dfrac{FL}{A\,\Delta L}$ , in pascal. It is a property of the material: about $200\ \text{GPa}$ for steel, $110$ for copper, $70$ for aluminium. A wire stretches $\Delta L = \dfrac{FL}{AY}$ , more if it is long, thin or of a soft material. Searle's apparatus measures $Y$ .
1 simulation2 practice questions1 Python program4 problems1 Python lab1 note
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Stress, Strain and Hooke's Law: Practice Paper

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Stress, Strain and Hooke's Law

Course outline (3 lessons)

Elasticity, stress and strain

Hooke's law and the stress-strain curve

Young's modulus and the stretching of wires

Test Your Learning

Your teacher

Discussion (0)